gemini-browser

textarea.go (79941B)

---

 package tview
 
 import (
 	"math"
 	"strings"
 	"unicode"
 	"unicode/utf8"
 
 	"github.com/gdamore/tcell/v2"
 	"github.com/rivo/uniseg"
 )
 
 const (
 	// The minimum capacity of the text area's piece chain slice.
 	pieceChainMinCap = 10
 
 	// The minimum capacity of the text area's edit buffer.
 	editBufferMinCap = 200
 
 	// The maximum number of bytes making up a grapheme cluster. In theory, this
 	// could be longer but it would be highly unusual.
 	maxGraphemeClusterSize = 40
 
 	// The default value for the [TextArea.minCursorPrefix] variable.
 	minCursorPrefixDefault = 5
 
 	// The default value for the [TextArea.minCursorSuffix] variable.
 	minCursorSuffixDefault = 3
 )
 
 // Types of user actions on a text area.
 type taAction int
 
 const (
 	taActionOther        taAction = iota
 	taActionTypeSpace             // Typing a space character.
 	taActionTypeNonSpace          // Typing a non-space character.
 	taActionBackspace             // Deleting the previous character.
 	taActionDelete                // Deleting the next character.
 )
 
 // NewLine is the string sequence to be inserted when hitting the Enter key in a
 // TextArea. The default is "\n" but you may change it to "\r\n" if required.
 var NewLine = "\n"
 
 // textAreaSpan represents a range of text in a text area. The text area widget
 // roughly follows the concept of Piece Chains outlined in
 // http://www.catch22.net/tuts/neatpad/piece-chains with some modifications.
 // This type represents a "span" (or "piece") and thus refers to a subset of the
 // text in the editor as part of a doubly-linked list.
 //
 // In most places where we reference a position in the text, we use a
 // three-element int array. The first element is the index of the referenced
 // span in the piece chain. The second element is the offset into the span's
 // referenced text (relative to the span's start), its value is always >= 0 and
 // < span.length. The third element is the state of the text parser at that
 // position.
 //
 // A range of text is represented by a span range which is a starting position
 // (3-int array) and an ending position (3-int array). The starting position
 // references the first character of the range, the ending position references
 // the position after the last character of the range. The end of the text is
 // therefore always [3]int{1, 0, 0}, position 0 of the ending sentinel.
 //
 // Sentinel spans are dummy spans not referring to any text. There are always
 // two sentinel spans: the starting span at index 0 of the [TextArea.spans]
 // slice and the ending span at index 1.
 type textAreaSpan struct {
 	// Links to the previous and next textAreaSpan objects as indices into the
 	// [TextArea.spans] slice. The sentinel spans (index 0 and 1) have -1 as
 	// their previous or next links, respectively.
 	previous, next int
 
 	// The start index and the length of the text segment this span represents.
 	// If "length" is negative, the span represents a substring of
 	// [TextArea.initialText] and the actual length is its absolute value. If it
 	// is positive, the span represents a substring of [TextArea.editText]. For
 	// the sentinel spans (index 0 and 1), both values will be 0. Others will
 	// never have a zero length.
 	offset, length int
 }
 
 // textAreaUndoItem represents an undoable edit to the text area. It describes
 // the two spans wrapping a text change.
 type textAreaUndoItem struct {
 	before, after                 int    // The index of the copied "before" and "after" spans into the "spans" slice.
 	originalBefore, originalAfter int    // The original indices of the "before" and "after" spans.
 	pos                           [3]int // The cursor position to be assumed after applying an undo.
 	length                        int    // The total text length at the time the undo item was created.
 	continuation                  bool   // If true, this item is a continuation of the previous undo item. It is handled together with all other undo items in the same continuation sequence.
 }
 
 // TextArea implements a simple text editor for multi-line text. Multi-color
 // text is not supported. Word-wrapping is enabled by default but can be turned
 // off or be changed to character-wrapping.
 //
 // # Navigation and Editing
 //
 // A text area is always in editing mode and no other mode exists. The following
 // keys can be used to move the cursor (subject to what the user's terminal
 // supports and how it is configured):
 //
 //   - Left arrow: Move left.
 //   - Right arrow: Move right.
 //   - Down arrow: Move down.
 //   - Up arrow: Move up.
 //   - Ctrl-A, Home: Move to the beginning of the current line.
 //   - Ctrl-E, End: Move to the end of the current line.
 //   - Ctrl-F, page down: Move down by one page.
 //   - Ctrl-B, page up: Move up by one page.
 //   - Alt-Up arrow: Scroll the page up, leaving the cursor in its position.
 //   - Alt-Down arrow: Scroll the page down, leaving the cursor in its position.
 //   - Alt-Left arrow: Scroll the page to the left, leaving the cursor in its
 //     position. Ignored if wrapping is enabled.
 //   - Alt-Right arrow:  Scroll the page to the right, leaving the cursor in its
 //     position. Ignored if wrapping is enabled.
 //   - Alt-B, Ctrl-Left arrow: Jump to the beginning of the current or previous
 //     word.
 //   - Alt-F, Ctrl-Right arrow: Jump to the end of the current or next word.
 //
 // Words are defined according to [Unicode Standard Annex #29]. We skip any
 // words that contain only spaces or punctuation.
 //
 // Entering a character will insert it at the current cursor location.
 // Subsequent characters are shifted accordingly. If the cursor is outside the
 // visible area, any changes to the text will move it into the visible area. The
 // following keys can also be used to modify the text:
 //
 //   - Enter: Insert a newline character (see [NewLine]).
 //   - Tab: Insert a tab character (\t). It will be rendered like [TabSize]
 //     spaces. (This may eventually be changed to behave like regular tabs.)
 //   - Ctrl-H, Backspace: Delete one character to the left of the cursor.
 //   - Ctrl-D, Delete: Delete the character under the cursor (or the first
 //     character on the next line if the cursor is at the end of a line).
 //   - Alt-Backspace: Delete the word to the left of the cursor.
 //   - Ctrl-K: Delete everything under and to the right of the cursor until the
 //     next newline character.
 //   - Ctrl-W: Delete from the start of the current word to the left of the
 //     cursor.
 //   - Ctrl-U: Delete the current line, i.e. everything after the last newline
 //     character before the cursor up until the next newline character. This may
 //     span multiple visible rows if wrapping is enabled.
 //
 // Text can be selected by moving the cursor while holding the Shift key, to the
 // extent that this is supported by the user's terminal. The Ctrl-L key can be
 // used to select the entire text. (Ctrl-A already binds to the "Home" key.)
 //
 // When text is selected:
 //
 //   - Entering a character will replace the selected text with the new
 //     character.
 //   - Backspace, delete, Ctrl-H, Ctrl-D: Delete the selected text.
 //   - Ctrl-Q: Copy the selected text into the clipboard, unselect the text.
 //   - Ctrl-X: Copy the selected text into the clipboard and delete it.
 //   - Ctrl-V: Replace the selected text with the clipboard text. If no text is
 //     selected, the clipboard text will be inserted at the cursor location.
 //
 // The Ctrl-Q key was chosen for the "copy" function because the Ctrl-C key is
 // the default key to stop the application. If your application frees up the
 // global Ctrl-C key and you want to bind it to the "copy to clipboard"
 // function, you may use [Box.SetInputCapture] to override the Ctrl-Q key to
 // implement copying to the clipboard. Note that using your terminal's /
 // operating system's key bindings for copy+paste functionality may not have the
 // expected effect as tview will not be able to handle these keys. Pasting text
 // using your operating system's or terminal's own methods may be very slow as
 // each character will be pasted individually. However, some terminals support
 // pasting text blocks which is supported by the text area, see
 // [Application.EnablePaste] for details.
 //
 // The default clipboard is an internal text buffer local to this text area
 // instance, i.e. the operating system's clipboard is not used. If you want to
 // implement your own clipboard (or make use of your operating system's
 // clipboard), you can use [TextArea.SetClipboard] which  provides all the
 // functionality needed to implement your own clipboard.
 //
 // The text area also supports Undo:
 //
 //   - Ctrl-Z: Undo the last change.
 //   - Ctrl-Y: Redo the last Undo change.
 //
 // Undo does not affect the clipboard.
 //
 // If the mouse is enabled, the following actions are available:
 //
 //   - Left click: Move the cursor to the clicked position or to the end of the
 //     line if past the last character.
 //   - Left double-click: Select the word under the cursor.
 //   - Left click while holding the Shift key: Select text.
 //   - Scroll wheel: Scroll the text.
 //
 // [Unicode Standard Annex #29]: https://unicode.org/reports/tr29/
 type TextArea struct {
 	*Box
 
 	// Whether or not this text area is disabled/read-only.
 	disabled bool
 
 	// The size of the text area. If set to 0, the text area will use the entire
 	// available space.
 	width, height int
 
 	// The text to be shown in the text area when it is empty.
 	placeholder string
 
 	// The label text shown, usually when part of a form.
 	label string
 
 	// The width of the text area's label.
 	labelWidth int
 
 	// Styles:
 
 	// The label style.
 	labelStyle tcell.Style
 
 	// The style of the text. Background colors different from the Box's
 	// background color may lead to unwanted artefacts.
 	textStyle tcell.Style
 
 	// The style of the selected text.
 	selectedStyle tcell.Style
 
 	// The style of the placeholder text.
 	placeholderStyle tcell.Style
 
 	// Text manipulation related fields:
 
 	// The text area's text prior to any editing. It is referenced by spans with
 	// a negative length.
 	initialText string
 
 	// Any text that's been added by the user at some point. We only ever append
 	// to this buffer. It is referenced by spans with a positive length.
 	editText strings.Builder
 
 	// The total length of all text in the text area.
 	length int
 
 	// The maximum number of bytes allowed in the text area. If 0, there is no
 	// limit.
 	maxLength int
 
 	// The piece chain. The first two spans are sentinel spans which don't
 	// reference anything and always remain in the same place. Spans are never
 	// deleted from this slice.
 	spans []textAreaSpan
 
 	// An optional function which transforms grapheme clusters. This can be used
 	// to hide characters from the screen while preserving the original text.
 	transform func(cluster, rest string, boundaries int) (newCluster string, newBoundaries int)
 
 	// Display, navigation, and cursor related fields:
 
 	// If set to true, lines that are longer than the available width are
 	// wrapped onto the next line. If set to false, any characters beyond the
 	// available width are discarded.
 	wrap bool
 
 	// If set to true and if wrap is also true, lines are split at spaces or
 	// after punctuation characters.
 	wordWrap bool
 
 	// The index of the first line shown in the text area.
 	rowOffset int
 
 	// The number of cells to be skipped on each line (not used in wrap mode).
 	columnOffset int
 
 	// The inner height and width of the text area the last time it was drawn.
 	lastHeight, lastWidth int
 
 	// The width of the currently known widest line, as determined by
 	// [TextArea.extendLines].
 	widestLine int
 
 	// Text positions and states of the start of lines. Each element is a span
 	// position (see [textAreaSpan]). Not all lines of the text may be contained
 	// at any time, extend as needed with the [TextArea.extendLines] function.
 	lineStarts [][3]int
 
 	// The cursor always points to the next position where a new character would
 	// be placed. The selection start is the same as the cursor as long as there
 	// is no selection. When there is one, the selection is between
 	// selectionStart and cursor.
 	cursor, selectionStart struct {
 		// The row and column in screen space but relative to the start of the
 		// text which may be outside the text area's box. The column value may
 		// be larger than where the cursor actually is if the line the cursor
 		// is on is shorter. The actualColumn is the position as it is seen on
 		// screen. These three values may not be determined yet, in which case
 		// the row is negative.
 		row, column, actualColumn int
 
 		// The textAreaSpan position with state for the actual next character.
 		pos [3]int
 	}
 
 	// The minimum width of text (if available) to be shown left of the cursor.
 	minCursorPrefix int
 
 	// The minimum width of text (if available) to be shown right of the cursor.
 	minCursorSuffix int
 
 	// Set to true when the mouse is dragging to select text.
 	dragging bool
 
 	// Clipboard related fields:
 
 	// The internal clipboard.
 	clipboard string
 
 	// The function to call when the user copies/cuts a text selection to the
 	// clipboard.
 	copyToClipboard func(string)
 
 	// The function to call when the user pastes text from the clipboard.
 	pasteFromClipboard func() string
 
 	// Undo/redo related fields:
 
 	// The last action performed by the user.
 	lastAction taAction
 
 	// The undo stack's items. Each item is a copy of the span before the
 	// modified span range and a copy of the span after the modified span range.
 	// To undo an action, the two referenced spans are put back into their
 	// original place. Undos and redos decrease or increase the nextUndo value.
 	// Thus, the next undo action is not always the last item.
 	undoStack []textAreaUndoItem
 
 	// The current undo/redo position on the undo stack. If no undo or redo has
 	// been performed yet, this is the same as len(undoStack).
 	nextUndo int
 
 	// Event handlers:
 
 	// An optional function which is called when the input has changed.
 	changed func()
 
 	// An optional function which is called when the position of the cursor or
 	// the selection has changed.
 	moved func()
 
 	// A callback function set by the Form class and called when the user leaves
 	// this form item.
 	finished func(tcell.Key)
 }
 
 // NewTextArea returns a new text area. Use [TextArea.SetText] to set the
 // initial text.
 func NewTextArea() *TextArea {
 	t := &TextArea{
 		Box:              NewBox(),
 		wrap:             true,
 		wordWrap:         true,
 		placeholderStyle: tcell.StyleDefault.Background(Styles.PrimitiveBackgroundColor).Foreground(Styles.TertiaryTextColor),
 		labelStyle:       tcell.StyleDefault.Foreground(Styles.SecondaryTextColor),
 		textStyle:        tcell.StyleDefault.Background(Styles.PrimitiveBackgroundColor).Foreground(Styles.PrimaryTextColor),
 		selectedStyle:    tcell.StyleDefault.Background(Styles.PrimaryTextColor).Foreground(Styles.PrimitiveBackgroundColor),
 		spans:            make([]textAreaSpan, 2, pieceChainMinCap), // We reserve some space to avoid reallocations right when editing starts.
 		lastAction:       taActionOther,
 		minCursorPrefix:  minCursorPrefixDefault,
 		minCursorSuffix:  minCursorSuffixDefault,
 		lastWidth:        math.MaxInt / 2, // We need this so some functions work before the first draw.
 		lastHeight:       1,
 	}
 	t.editText.Grow(editBufferMinCap)
 	t.spans[0] = textAreaSpan{previous: -1, next: 1}
 	t.spans[1] = textAreaSpan{previous: 0, next: -1}
 	t.cursor.pos = [3]int{1, 0, -1}
 	t.selectionStart = t.cursor
 	t.SetClipboard(nil, nil)
 
 	return t
 }
 
 // SetText sets the text of the text area. All existing text is deleted and
 // replaced with the new text. Any edits are discarded, no undos are available.
 // This function is typically only used to initialize the text area with a text
 // after it has been created. To clear the text area's text (again, no undos),
 // provide an empty string.
 //
 // If cursorAtTheEnd is false, the cursor is placed at the start of the text. If
 // it is true, it is placed at the end of the text. For very long texts, placing
 // the cursor at the end can be an expensive operation because the entire text
 // needs to be parsed and laid out.
 //
 // If you want to set text and preserve undo functionality, use
 // [TextArea.Replace] instead.
 func (t *TextArea) SetText(text string, cursorAtTheEnd bool) *TextArea {
 	t.spans = t.spans[:2]
 	t.initialText = text
 	t.editText.Reset()
 	t.lineStarts = nil
 	t.length = len(text)
 	t.rowOffset = 0
 	t.columnOffset = 0
 	t.reset()
 	t.cursor.row, t.cursor.actualColumn, t.cursor.column = 0, 0, 0
 	t.cursor.pos = [3]int{1, 0, -1}
 	t.undoStack = t.undoStack[:0]
 	t.nextUndo = 0
 
 	if len(text) > 0 {
 		t.spans = append(t.spans, textAreaSpan{
 			previous: 0,
 			next:     1,
 			offset:   0,
 			length:   -len(text),
 		})
 		t.spans[0].next = 2
 		t.spans[1].previous = 2
 		if cursorAtTheEnd {
 			t.cursor.row = -1
 			if t.lastWidth > 0 {
 				t.findCursor(true, 0)
 			}
 		} else {
 			t.cursor.pos = [3]int{2, 0, -1}
 		}
 	} else {
 		t.spans[0].next = 1
 		t.spans[1].previous = 0
 	}
 	t.selectionStart = t.cursor
 
 	if t.changed != nil {
 		t.changed()
 	}
 
 	if t.lastWidth > 0 && t.moved != nil {
 		t.moved()
 	}
 
 	return t
 }
 
 // GetText returns the entire text of the text area. Note that this will newly
 // allocate the entire text.
 func (t *TextArea) GetText() string {
 	if t.length == 0 {
 		return ""
 	}
 
 	var text strings.Builder
 	text.Grow(t.length)
 	spanIndex := t.spans[0].next
 	for spanIndex != 1 {
 		span := &t.spans[spanIndex]
 		if span.length < 0 {
 			text.WriteString(t.initialText[span.offset : span.offset-span.length])
 		} else {
 			text.WriteString(t.editText.String()[span.offset : span.offset+span.length])
 		}
 		spanIndex = t.spans[spanIndex].next
 	}
 
 	return text.String()
 }
 
 // getTextBeforeCursor returns the text of the text area up until the cursor.
 // Note that this will result in a new allocation for the returned text.
 func (t *TextArea) getTextBeforeCursor() string {
 	if t.length == 0 || t.cursor.pos[0] == t.spans[0].next && t.cursor.pos[1] == 0 {
 		return ""
 	}
 
 	var text strings.Builder
 	spanIndex := t.spans[0].next
 	for spanIndex != 1 {
 		span := &t.spans[spanIndex]
 		length := span.length
 		if length < 0 {
 			if t.cursor.pos[0] == spanIndex {
 				length = -t.cursor.pos[1]
 			}
 			text.WriteString(t.initialText[span.offset : span.offset-length])
 		} else {
 			if t.cursor.pos[0] == spanIndex {
 				length = t.cursor.pos[1]
 			}
 			text.WriteString(t.editText.String()[span.offset : span.offset+length])
 		}
 		if t.cursor.pos[0] == spanIndex {
 			break
 		}
 		spanIndex = t.spans[spanIndex].next
 	}
 
 	return text.String()
 }
 
 // getTextAfterCursor returns the text of the text area after the cursor. Note
 // that this will result in a new allocation for the returned text.
 func (t *TextArea) getTextAfterCursor() string {
 	if t.length == 0 || t.cursor.pos[0] == 1 {
 		return ""
 	}
 
 	var text strings.Builder
 	spanIndex := t.cursor.pos[0]
 	cursorOffset := t.cursor.pos[1]
 	for spanIndex != 1 {
 		span := &t.spans[spanIndex]
 		length := span.length
 		if length < 0 {
 			text.WriteString(t.initialText[span.offset+cursorOffset : span.offset-length])
 		} else {
 			text.WriteString(t.editText.String()[span.offset+cursorOffset : span.offset+length])
 		}
 		spanIndex = t.spans[spanIndex].next
 		cursorOffset = 0
 	}
 
 	return text.String()
 }
 
 // HasSelection returns whether the selected text is non-empty.
 func (t *TextArea) HasSelection() bool {
 	return t.selectionStart != t.cursor
 }
 
 // GetSelection returns the currently selected text and its start and end
 // positions within the entire text as a half-open interval. If the returned
 // text is an empty string, the start and end positions are the same and can be
 // interpreted as the cursor position.
 //
 // Calling this function will result in string allocations as well as a search
 // for text positions. This is expensive if the text has been edited extensively
 // already. Use [TextArea.HasSelection] first if you are only interested in
 // selected text.
 func (t *TextArea) GetSelection() (text string, start int, end int) {
 	from, to := t.selectionStart.pos, t.cursor.pos
 	if t.cursor.row < t.selectionStart.row || (t.cursor.row == t.selectionStart.row && t.cursor.actualColumn < t.selectionStart.actualColumn) {
 		from, to = to, from
 	}
 
 	if from[0] == 1 {
 		start = t.length
 	}
 	if to[0] == 1 {
 		end = t.length
 	}
 
 	var (
 		index     int
 		selection strings.Builder
 		inside    bool
 	)
 	for span := t.spans[0].next; span != 1; span = t.spans[span].next {
 		var spanText string
 		length := t.spans[span].length
 		if length < 0 {
 			length = -length
 			spanText = t.initialText
 		} else {
 			spanText = t.editText.String()
 		}
 		spanText = spanText[t.spans[span].offset : t.spans[span].offset+length]
 
 		if from[0] == span && to[0] == span {
 			if from != to {
 				selection.WriteString(spanText[from[1]:to[1]])
 			}
 			start = index + from[1]
 			end = index + to[1]
 			break
 		} else if from[0] == span {
 			if from != to {
 				selection.WriteString(spanText[from[1]:])
 			}
 			start = index + from[1]
 			inside = true
 		} else if to[0] == span {
 			if from != to {
 				selection.WriteString(spanText[:to[1]])
 			}
 			end = index + to[1]
 			break
 		} else if inside && from != to {
 			selection.WriteString(spanText)
 		}
 
 		index += length
 	}
 
 	if selection.Len() != 0 {
 		text = selection.String()
 	}
 	return
 }
 
 // GetCursor returns the current cursor position where the first character of
 // the entire text is in row 0, column 0. If the user has selected text, the
 // "from" values will refer to the beginning of the selection and the "to"
 // values to the end of the selection (exclusive). They are the same if there
 // is no selection.
 func (t *TextArea) GetCursor() (fromRow, fromColumn, toRow, toColumn int) {
 	fromRow, fromColumn = t.selectionStart.row, t.selectionStart.actualColumn
 	toRow, toColumn = t.cursor.row, t.cursor.actualColumn
 	if toRow < fromRow || (toRow == fromRow && toColumn < fromColumn) {
 		fromRow, fromColumn, toRow, toColumn = toRow, toColumn, fromRow, fromColumn
 	}
 	if t.length > 0 && t.wrap && fromColumn >= t.lastWidth { // This happens when a row has text all the way until the end, pushing the cursor outside the viewport.
 		fromRow++
 		fromColumn = 0
 	}
 	if t.length > 0 && t.wrap && toColumn >= t.lastWidth {
 		toRow++
 		toColumn = 0
 	}
 	return
 }
 
 // GetTextLength returns the string length of the text in the text area.
 func (t *TextArea) GetTextLength() int {
 	return t.length
 }
 
 // Replace replaces a section of the text with new text. The start and end
 // positions refer to index positions within the entire text string (as a
 // half-open interval). They may be the same, in which case text is inserted at
 // the given position. If the text is an empty string, text between start and
 // end is deleted. Index positions will be shifted to line up with character
 // boundaries. A "changed" event will be triggered.
 //
 // Previous selections are cleared. The cursor will be located at the end of the
 // replaced text. Scroll offsets will not be changed. A "moved" event will be
 // triggered.
 //
 // The effects of this function can be undone (and redone) by the user.
 func (t *TextArea) Replace(start, end int, text string) *TextArea {
 	t.Select(start, end)
 	row := t.selectionStart.row
 	t.cursor.pos = t.replace(t.selectionStart.pos, t.cursor.pos, text, false)
 	t.cursor.row = -1
 	t.truncateLines(row - 1)
 	t.findCursor(false, row)
 	t.selectionStart = t.cursor
 	if t.moved != nil {
 		t.moved()
 	}
 	// The "changed" event will have been triggered by the "replace" function.
 	return t
 }
 
 // Select selects a section of the text. The start and end positions refer to
 // index positions within the entire text string (as a half-open interval). They
 // may be the same, in which case the cursor is placed at the given position.
 // Any previous selection is removed. Scroll offsets will be preserved.
 //
 // Index positions will be shifted to line up with character boundaries.
 func (t *TextArea) Select(start, end int) *TextArea {
 	oldFrom, oldTo := t.selectionStart, t.cursor
 	defer func() {
 		if (oldFrom != t.selectionStart || oldTo != t.cursor) && t.moved != nil {
 			t.moved()
 		}
 	}()
 
 	// Clamp input values.
 	if start < 0 {
 		start = 0
 	}
 	if start > t.length {
 		start = t.length
 	}
 	if end < 0 {
 		end = 0
 	}
 	if end > t.length {
 		end = t.length
 	}
 	if end < start {
 		start, end = end, start
 	}
 
 	// Find the cursor positions.
 	var row, index int
 	t.cursor.row, t.cursor.pos = -1, [3]int{1, 0, -1}
 	t.selectionStart = t.cursor
 RowLoop:
 	for {
 		if row >= len(t.lineStarts) {
 			t.extendLines(t.lastWidth, row)
 			if row >= len(t.lineStarts) {
 				break
 			}
 		}
 
 		// Check the spans of this row.
 		pos := t.lineStarts[row]
 		var (
 			next      [3]int
 			lineIndex int
 		)
 		if row+1 < len(t.lineStarts) {
 			next = t.lineStarts[row+1]
 		} else {
 			next = [3]int{1, 0, -1}
 		}
 		for {
 			if pos[0] == next[0] {
 				if start >= index+lineIndex && start < index+lineIndex+next[1]-pos[1] ||
 					end >= index+lineIndex && end < index+lineIndex+next[1]-pos[1] ||
 					next[0] == 1 && (start == t.length || end == t.length) { // Special case for the end of the text.
 					break
 				}
 				index += lineIndex + next[1] - pos[1]
 				row++
 				continue RowLoop // Move on to the next row.
 			} else {
 				length := t.spans[pos[0]].length
 				if length < 0 {
 					length = -length
 				}
 				if start >= index+lineIndex && start < index+lineIndex+length-pos[1] ||
 					end >= index+lineIndex && end < index+lineIndex+length-pos[1] ||
 					next[0] == 1 && (start == t.length || end == t.length) { // Special case for the end of the text.
 					break
 				}
 				lineIndex += length - pos[1]
 				pos[0], pos[1] = t.spans[pos[0]].next, 0
 			}
 		}
 
 		// One of the indices is in this row. Step through it.
 		pos = t.lineStarts[row]
 		endPos := pos
 		var (
 			cluster, text string
 			column, width int
 		)
 		for pos != next {
 			if t.selectionStart.row < 0 && start <= index {
 				t.selectionStart.row, t.selectionStart.column, t.selectionStart.actualColumn = row, column, column
 				t.selectionStart.pos = pos
 			}
 			if t.cursor.row < 0 && end <= index {
 				t.cursor.row, t.cursor.column, t.cursor.actualColumn = row, column, column
 				t.cursor.pos = pos
 				break RowLoop
 			}
 			cluster, text, _, width, pos, endPos = t.step(text, pos, endPos)
 			index += len(cluster)
 			column += width
 		}
 		row++
 	}
 
 	if t.cursor.row < 0 {
 		t.findCursor(false, 0) // This only happens if we couldn't find the locations above.
 		t.selectionStart = t.cursor
 	}
 
 	return t
 }
 
 // SetWrap sets the flag that, if true, leads to lines that are longer than the
 // available width being wrapped onto the next line. If false, any characters
 // beyond the available width are not displayed.
 func (t *TextArea) SetWrap(wrap bool) *TextArea {
 	if t.wrap != wrap {
 		t.wrap = wrap
 		t.reset()
 	}
 	return t
 }
 
 // SetWordWrap sets the flag that causes lines that are longer than the
 // available width to be wrapped onto the next line at spaces or after
 // punctuation marks (according to [Unicode Standard Annex #14]). This flag is
 // ignored if the flag set with [TextArea.SetWrap] is false. The text area's
 // default is word-wrapping.
 //
 // [Unicode Standard Annex #14]: https://www.unicode.org/reports/tr14/
 func (t *TextArea) SetWordWrap(wrapOnWords bool) *TextArea {
 	if t.wordWrap != wrapOnWords {
 		t.wordWrap = wrapOnWords
 		t.reset()
 	}
 	return t
 }
 
 // SetPlaceholder sets the text to be displayed when the text area is empty.
 func (t *TextArea) SetPlaceholder(placeholder string) *TextArea {
 	t.placeholder = placeholder
 	return t
 }
 
 // SetLabel sets the text to be displayed before the text area.
 func (t *TextArea) SetLabel(label string) *TextArea {
 	t.label = label
 	return t
 }
 
 // GetLabel returns the text to be displayed before the text area.
 func (t *TextArea) GetLabel() string {
 	return t.label
 }
 
 // SetLabelWidth sets the screen width of the label. A value of 0 will cause the
 // primitive to use the width of the label string.
 func (t *TextArea) SetLabelWidth(width int) *TextArea {
 	t.labelWidth = width
 	return t
 }
 
 // GetLabelWidth returns the screen width of the label.
 func (t *TextArea) GetLabelWidth() int {
 	return t.labelWidth
 }
 
 // SetSize sets the screen size of the input element of the text area. The input
 // element is always located next to the label which is always located in the
 // top left corner. If any of the values are 0 or larger than the available
 // space, the available space will be used.
 func (t *TextArea) SetSize(rows, columns int) *TextArea {
 	t.width = columns
 	t.height = rows
 	return t
 }
 
 // GetFieldWidth returns this primitive's field width.
 func (t *TextArea) GetFieldWidth() int {
 	return t.width
 }
 
 // GetFieldHeight returns this primitive's field height.
 func (t *TextArea) GetFieldHeight() int {
 	return t.height
 }
 
 // SetDisabled sets whether or not the item is disabled / read-only.
 func (t *TextArea) SetDisabled(disabled bool) FormItem {
 	t.disabled = disabled
 	if t.finished != nil {
 		t.finished(-1)
 	}
 	return t
 }
 
 // GetDisabled returns whether or not the item is disabled / read-only.
 func (t *TextArea) GetDisabled() bool {
 	return t.disabled
 }
 
 // SetMaxLength sets the maximum number of bytes allowed in the text area. A
 // value of 0 means there is no limit. If the text area currently contains more
 // bytes than this, it may violate this constraint.
 func (t *TextArea) SetMaxLength(maxLength int) *TextArea {
 	t.maxLength = maxLength
 	return t
 }
 
 // setMinCursorPadding sets a minimum width to be reserved left and right of the
 // cursor. This is ignored if wrapping is enabled.
 func (t *TextArea) setMinCursorPadding(prefix, suffix int) *TextArea {
 	t.minCursorPrefix = prefix
 	t.minCursorSuffix = suffix
 	return t
 }
 
 // SetLabelStyle sets the style of the label.
 func (t *TextArea) SetLabelStyle(style tcell.Style) *TextArea {
 	t.labelStyle = style
 	return t
 }
 
 // GetLabelStyle returns the style of the label.
 func (t *TextArea) GetLabelStyle() tcell.Style {
 	return t.labelStyle
 }
 
 // SetTextStyle sets the style of the text.
 func (t *TextArea) SetTextStyle(style tcell.Style) *TextArea {
 	t.textStyle = style
 	return t
 }
 
 // GetTextStyle returns the style of the text.
 func (t *TextArea) GetTextStyle() tcell.Style {
 	return t.textStyle
 }
 
 // SetSelectedStyle sets the style of the selected text.
 func (t *TextArea) SetSelectedStyle(style tcell.Style) *TextArea {
 	t.selectedStyle = style
 	return t
 }
 
 // SetPlaceholderStyle sets the style of the placeholder text.
 func (t *TextArea) SetPlaceholderStyle(style tcell.Style) *TextArea {
 	t.placeholderStyle = style
 	return t
 }
 
 // GetPlaceholderStyle returns the style of the placeholder text.
 func (t *TextArea) GetPlaceholderStyle() tcell.Style {
 	return t.placeholderStyle
 }
 
 // GetOffset returns the text's offset, that is, the number of rows and columns
 // skipped during drawing at the top or on the left, respectively. Note that the
 // column offset is ignored if wrapping is enabled.
 func (t *TextArea) GetOffset() (row, column int) {
 	return t.rowOffset, t.columnOffset
 }
 
 // SetOffset sets the text's offset, that is, the number of rows and columns
 // skipped during drawing at the top or on the left, respectively. If wrapping
 // is enabled, the column offset is ignored. These values may get adjusted
 // automatically to ensure that some text is always visible.
 func (t *TextArea) SetOffset(row, column int) *TextArea {
 	t.rowOffset, t.columnOffset = row, column
 	return t
 }
 
 // SetClipboard allows you to implement your own clipboard by providing a
 // function that is called when the user wishes to store text in the clipboard
 // (copyToClipboard) and a function that is called when the user wishes to
 // retrieve text from the clipboard (pasteFromClipboard).
 //
 // Providing nil values will cause the default clipboard implementation to be
 // used. Note that the default clipboard is local to this text area instance.
 // Copying text to other widgets will not work.
 func (t *TextArea) SetClipboard(copyToClipboard func(string), pasteFromClipboard func() string) *TextArea {
 	t.copyToClipboard = copyToClipboard
 	if t.copyToClipboard == nil {
 		t.copyToClipboard = func(text string) {
 			t.clipboard = text
 		}
 	}
 
 	t.pasteFromClipboard = pasteFromClipboard
 	if t.pasteFromClipboard == nil {
 		t.pasteFromClipboard = func() string {
 			return t.clipboard
 		}
 	}
 
 	return t
 }
 
 // GetClipboardText returns the current text of the clipboard by calling the
 // pasteFromClipboard function set with [TextArea.SetClipboard].
 func (t *TextArea) GetClipboardText() string {
 	return t.pasteFromClipboard()
 }
 
 // SetChangedFunc sets a handler which is called whenever the text of the text
 // area has changed.
 func (t *TextArea) SetChangedFunc(handler func()) *TextArea {
 	t.changed = handler
 	return t
 }
 
 // SetMovedFunc sets a handler which is called whenever the cursor position or
 // the text selection has changed.
 func (t *TextArea) SetMovedFunc(handler func()) *TextArea {
 	t.moved = handler
 	return t
 }
 
 // SetFinishedFunc sets a callback invoked when the user leaves this form item.
 func (t *TextArea) SetFinishedFunc(handler func(key tcell.Key)) FormItem {
 	t.finished = handler
 	return t
 }
 
 // Focus is called when this primitive receives focus.
 func (t *TextArea) Focus(delegate func(p Primitive)) {
 	// If we're part of a form and this item is disabled, there's nothing the
 	// user can do here so we're finished.
 	if t.finished != nil && t.disabled {
 		t.finished(-1)
 		return
 	}
 
 	t.Box.Focus(delegate)
 }
 
 // SetFormAttributes sets attributes shared by all form items.
 func (t *TextArea) SetFormAttributes(labelWidth int, labelColor, bgColor, fieldTextColor, fieldBgColor tcell.Color) FormItem {
 	t.labelWidth = labelWidth
 	t.backgroundColor = bgColor
 	t.labelStyle = t.labelStyle.Foreground(labelColor)
 	t.textStyle = tcell.StyleDefault.Foreground(fieldTextColor).Background(fieldBgColor)
 	return t
 }
 
 // replace deletes a range of text and inserts the given text at that position.
 // If the resulting text would exceed the maximum length, the function does not
 // do anything. The function returns the end position of the deleted/inserted
 // range.
 //
 // The function can hang if "deleteStart" is located after "deleteEnd".
 //
 // Undo events are always generated unless continuation is true and text is
 // either appended to the end of a span or a span is shortened at the beginning
 // or the end (and nothing else).
 //
 // This function only modifies [TextArea.lineStarts] to update span references
 // but does not change it to reflect the new layout.
 //
 // A "changed" event will be triggered.
 func (t *TextArea) replace(deleteStart, deleteEnd [3]int, insert string, continuation bool) [3]int {
 	// Maybe nothing needs to be done?
 	if deleteStart == deleteEnd && insert == "" || t.maxLength > 0 && len(insert) > 0 && t.length+len(insert) >= t.maxLength {
 		return deleteEnd
 	}
 
 	// Notify at the end.
 	if t.changed != nil {
 		defer t.changed()
 	}
 
 	// Handle a few cases where we don't put anything onto the undo stack for
 	// increased efficiency.
 	if continuation {
 		// Same action as the one before. An undo item was already generated for
 		// this block of (same) actions. We're also only changing one character.
 		switch {
 		case insert == "" && deleteStart[1] != 0 && deleteEnd[1] == 0:
 			// Simple backspace. Just shorten this span.
 			length := t.spans[deleteStart[0]].length
 			if length < 0 {
 				t.length -= -length - deleteStart[1]
 				length = -deleteStart[1]
 			} else {
 				t.length -= length - deleteStart[1]
 				length = deleteStart[1]
 			}
 			t.spans[deleteStart[0]].length = length
 			return deleteEnd
 		case insert == "" && deleteStart[1] == 0 && deleteEnd[1] != 0:
 			// Simple delete. Just clip the beginning of this span.
 			t.spans[deleteEnd[0]].offset += deleteEnd[1]
 			if t.spans[deleteEnd[0]].length < 0 {
 				t.spans[deleteEnd[0]].length += deleteEnd[1]
 			} else {
 				t.spans[deleteEnd[0]].length -= deleteEnd[1]
 			}
 			t.length -= deleteEnd[1]
 			deleteEnd[1] = 0
 			return deleteEnd
 		case insert != "" && deleteStart == deleteEnd && deleteEnd[1] == 0:
 			previous := t.spans[deleteStart[0]].previous
 			bufferSpan := t.spans[previous]
 			if bufferSpan.length > 0 && bufferSpan.offset+bufferSpan.length == t.editText.Len() {
 				// Typing individual characters. Simply extend the edit buffer.
 				length, _ := t.editText.WriteString(insert)
 				t.spans[previous].length += length
 				t.length += length
 				return deleteEnd
 			}
 		}
 	}
 
 	// All other cases generate an undo item.
 	before := t.spans[deleteStart[0]].previous
 	after := deleteEnd[0]
 	if deleteEnd[1] > 0 {
 		after = t.spans[deleteEnd[0]].next
 	}
 	t.undoStack = t.undoStack[:t.nextUndo]
 	t.undoStack = append(t.undoStack, textAreaUndoItem{
 		before:         len(t.spans),
 		after:          len(t.spans) + 1,
 		originalBefore: before,
 		originalAfter:  after,
 		length:         t.length,
 		pos:            t.cursor.pos,
 		continuation:   continuation,
 	})
 	t.spans = append(t.spans, t.spans[before])
 	t.spans = append(t.spans, t.spans[after])
 	t.nextUndo++
 
 	// Adjust total text length by subtracting everything between "before" and
 	// "after". Inserted spans will be added back.
 	for index := deleteStart[0]; index != after; index = t.spans[index].next {
 		if t.spans[index].length < 0 {
 			t.length += t.spans[index].length
 		} else {
 			t.length -= t.spans[index].length
 		}
 	}
 	t.spans[before].next = after
 	t.spans[after].previous = before
 
 	// We go from left to right, connecting new spans as needed. We update
 	// "before" as the span to connect new spans to.
 
 	// If we start deleting in the middle of a span, connect a partial span.
 	if deleteStart[1] != 0 {
 		span := textAreaSpan{
 			previous: before,
 			next:     after,
 			offset:   t.spans[deleteStart[0]].offset,
 			length:   deleteStart[1],
 		}
 		if t.spans[deleteStart[0]].length < 0 {
 			span.length = -span.length
 		}
 		t.length += deleteStart[1] // This was previously subtracted.
 		t.spans[before].next = len(t.spans)
 		t.spans[after].previous = len(t.spans)
 		before = len(t.spans)
 		for row, lineStart := range t.lineStarts { // Also redirect line starts until the end of this new span.
 			if lineStart[0] == deleteStart[0] {
 				if lineStart[1] >= deleteStart[1] {
 					t.lineStarts = t.lineStarts[:row] // Everything else is unknown at this point.
 					break
 				}
 				t.lineStarts[row][0] = len(t.spans)
 			}
 		}
 		t.spans = append(t.spans, span)
 	}
 
 	// If we insert text, connect a new span.
 	if insert != "" {
 		span := textAreaSpan{
 			previous: before,
 			next:     after,
 			offset:   t.editText.Len(),
 		}
 		span.length, _ = t.editText.WriteString(insert)
 		t.length += span.length
 		t.spans[before].next = len(t.spans)
 		t.spans[after].previous = len(t.spans)
 		before = len(t.spans)
 		t.spans = append(t.spans, span)
 	}
 
 	// If we stop deleting in the middle of a span, connect a partial span.
 	if deleteEnd[1] != 0 {
 		span := textAreaSpan{
 			previous: before,
 			next:     after,
 			offset:   t.spans[deleteEnd[0]].offset + deleteEnd[1],
 		}
 		length := t.spans[deleteEnd[0]].length
 		if length < 0 {
 			span.length = length + deleteEnd[1]
 			t.length -= span.length // This was previously subtracted.
 		} else {
 			span.length = length - deleteEnd[1]
 			t.length += span.length // This was previously subtracted.
 		}
 		t.spans[before].next = len(t.spans)
 		t.spans[after].previous = len(t.spans)
 		deleteEnd[0], deleteEnd[1] = len(t.spans), 0
 		t.spans = append(t.spans, span)
 	}
 
 	return deleteEnd
 }
 
 // Draw draws this primitive onto the screen.
 func (t *TextArea) Draw(screen tcell.Screen) {
 	t.Box.DrawForSubclass(screen, t)
 
 	// Prepare
 	x, y, width, height := t.GetInnerRect()
 	if width <= 0 || height <= 0 {
 		return // We have no space for anything.
 	}
 	columnOffset := t.columnOffset
 	if t.wrap {
 		columnOffset = 0
 	}
 
 	// Draw label.
 	_, labelBg, _ := t.labelStyle.Decompose()
 	if t.labelWidth > 0 {
 		labelWidth := t.labelWidth
 		if labelWidth > width {
 			labelWidth = width
 		}
 		printWithStyle(screen, t.label, x, y, 0, labelWidth, AlignLeft, t.labelStyle, labelBg == tcell.ColorDefault)
 		x += labelWidth
 		width -= labelWidth
 	} else {
 		_, _, drawnWidth := printWithStyle(screen, t.label, x, y, 0, width, AlignLeft, t.labelStyle, labelBg == tcell.ColorDefault)
 		x += drawnWidth
 		width -= drawnWidth
 	}
 
 	// What's the space for the input element?
 	if t.width > 0 && t.width < width {
 		width = t.width
 	}
 	if t.height > 0 && t.height < height {
 		height = t.height
 	}
 	if width <= 0 {
 		return // No space left for the text area.
 	}
 
 	// Draw the input element if necessary.
 	_, bg, _ := t.textStyle.Decompose()
 	if t.disabled {
 		bg = t.backgroundColor
 	}
 	if bg != t.backgroundColor {
 		for row := 0; row < height; row++ {
 			for column := 0; column < width; column++ {
 				screen.SetContent(x+column, y+row, ' ', nil, t.textStyle)
 			}
 		}
 	}
 
 	// Show/hide the cursor at the end.
 	defer func() {
 		if t.HasFocus() {
 			row, column := t.cursor.row, t.cursor.actualColumn
 			if t.length > 0 && t.wrap && column >= t.lastWidth { // This happens when a row has text all the way until the end, pushing the cursor outside the viewport.
 				row++
 				column = 0
 			}
 			if row >= 0 &&
 				row-t.rowOffset >= 0 && row-t.rowOffset < height &&
 				column-columnOffset >= 0 && column-columnOffset < width {
 				screen.ShowCursor(x+column-columnOffset, y+row-t.rowOffset)
 			} else {
 				screen.HideCursor()
 			}
 		}
 	}()
 
 	// No text, show placeholder.
 	if t.length == 0 {
 		t.lastHeight, t.lastWidth = height, width
 		t.cursor.row, t.cursor.column, t.cursor.actualColumn, t.cursor.pos = 0, 0, 0, [3]int{1, 0, -1}
 		t.rowOffset, t.columnOffset = 0, 0
 		if len(t.placeholder) > 0 {
 			t.drawPlaceholder(screen, x, y, width, height)
 		}
 		return // We're done already.
 	}
 
 	// Make sure the visible lines are broken over.
 	firstDrawing := t.lastWidth == 0
 	if t.lastWidth != width && t.lineStarts != nil {
 		t.reset()
 	}
 	t.lastHeight, t.lastWidth = height, width
 	t.extendLines(width, t.rowOffset+height)
 	if len(t.lineStarts) <= t.rowOffset {
 		return // It's scrolled out of view.
 	}
 
 	// If the cursor position is unknown, find it. This usually only happens
 	// before the screen is drawn for the first time.
 	if t.cursor.row < 0 {
 		t.findCursor(true, 0)
 		if t.selectionStart.row < 0 {
 			t.selectionStart = t.cursor
 		}
 		if firstDrawing && t.moved != nil {
 			t.moved()
 		}
 	}
 
 	// Print the text.
 	var cluster, text string
 	line := t.rowOffset
 	pos := t.lineStarts[line]
 	endPos := pos
 	posX, posY := 0, 0
 	for pos[0] != 1 {
 		var clusterWidth int
 		cluster, text, _, clusterWidth, pos, endPos = t.step(text, pos, endPos)
 
 		// Prepare drawing.
 		runes := []rune(cluster)
 		style := t.selectedStyle
 		fromRow, fromColumn := t.cursor.row, t.cursor.actualColumn
 		toRow, toColumn := t.selectionStart.row, t.selectionStart.actualColumn
 		if fromRow > toRow || fromRow == toRow && fromColumn > toColumn {
 			fromRow, fromColumn, toRow, toColumn = toRow, toColumn, fromRow, fromColumn
 		}
 		if toRow < line ||
 			toRow == line && toColumn <= posX ||
 			fromRow > line ||
 			fromRow == line && fromColumn > posX {
 			style = t.textStyle
 			if t.disabled {
 				style = style.Background(t.backgroundColor)
 			}
 		}
 
 		// Selected tabs are a bit special.
 		if cluster == "\t" && style == t.selectedStyle {
 			for colX := 0; colX < clusterWidth && posX+colX-columnOffset < width; colX++ {
 				screen.SetContent(x+posX+colX-columnOffset, y+posY, ' ', nil, style)
 			}
 		}
 
 		// Draw character.
 		if posX+clusterWidth-columnOffset <= width && posX-columnOffset >= 0 && clusterWidth > 0 {
 			screen.SetContent(x+posX-columnOffset, y+posY, runes[0], runes[1:], style)
 		}
 
 		// Advance.
 		posX += clusterWidth
 		if line+1 < len(t.lineStarts) && t.lineStarts[line+1] == pos {
 			// We must break over.
 			posY++
 			if posY >= height {
 				break // Done.
 			}
 			posX = 0
 			line++
 		}
 	}
 }
 
 // drawPlaceholder draws the placeholder text into the given rectangle. It does
 // not do anything if the text area already contains text or if there is no
 // placeholder text.
 func (t *TextArea) drawPlaceholder(screen tcell.Screen, x, y, width, height int) {
 	// We use a TextView to draw the placeholder. It will take care of word
 	// wrapping etc.
 	textView := NewTextView().
 		SetText(t.placeholder).
 		SetTextStyle(t.placeholderStyle)
 	textView.SetRect(x, y, width, height)
 	textView.Draw(screen)
 }
 
 // reset resets many of the local variables of the text area because they cannot
 // be used anymore and must be recalculated, typically after the text area's
 // size has changed.
 func (t *TextArea) reset() {
 	t.truncateLines(0)
 	if t.wrap {
 		t.cursor.row = -1
 		t.selectionStart.row = -1
 	}
 	t.widestLine = 0
 }
 
 // extendLines traverses the current text and extends [TextArea.lineStarts] such
 // that it describes at least maxLines+1 lines (or less if the text is shorter).
 // Text is laid out for the given width while respecting the wrapping settings.
 // It is assumed that if [TextArea.lineStarts] already has entries, they obey
 // the same rules.
 //
 // If width is 0, nothing happens.
 func (t *TextArea) extendLines(width, maxLines int) {
 	if width <= 0 {
 		return
 	}
 
 	// Start with the first span.
 	if len(t.lineStarts) == 0 {
 		if len(t.spans) > 2 {
 			t.lineStarts = append(t.lineStarts, [3]int{t.spans[0].next, 0, -1})
 		} else {
 			return // No text.
 		}
 	}
 
 	// Determine starting positions and starting spans.
 	pos := t.lineStarts[len(t.lineStarts)-1] // The starting position is the last known line.
 	endPos := pos
 	var (
 		cluster, text                       string
 		lineWidth, clusterWidth, boundaries int
 		lastGraphemeBreak, lastLineBreak    [3]int
 		widthSinceLineBreak                 int
 	)
 	for pos[0] != 1 {
 		// Get the next grapheme cluster.
 		cluster, text, boundaries, clusterWidth, pos, endPos = t.step(text, pos, endPos)
 		lineWidth += clusterWidth
 		widthSinceLineBreak += clusterWidth
 
 		// Any line breaks?
 		if !t.wrap || lineWidth <= width {
 			if boundaries&uniseg.MaskLine == uniseg.LineMustBreak && (len(text) > 0 || uniseg.HasTrailingLineBreakInString(cluster)) {
 				// We must break over.
 				t.lineStarts = append(t.lineStarts, pos)
 				if lineWidth > t.widestLine {
 					t.widestLine = lineWidth
 				}
 				lineWidth = 0
 				lastGraphemeBreak = [3]int{}
 				lastLineBreak = [3]int{}
 				widthSinceLineBreak = 0
 				if len(t.lineStarts) > maxLines {
 					break // We have enough lines, we can stop.
 				}
 				continue
 			}
 		} else { // t.wrap && lineWidth > width
 			if !t.wordWrap || lastLineBreak == [3]int{} {
 				if lastGraphemeBreak != [3]int{} { // We have at least one character on each line.
 					// Break after last grapheme.
 					t.lineStarts = append(t.lineStarts, lastGraphemeBreak)
 					if lineWidth > t.widestLine {
 						t.widestLine = lineWidth
 					}
 					lineWidth = clusterWidth
 					lastLineBreak = [3]int{}
 				}
 			} else { // t.wordWrap && lastLineBreak != [3]int{}
 				// Break after last line break opportunity.
 				t.lineStarts = append(t.lineStarts, lastLineBreak)
 				if lineWidth > t.widestLine {
 					t.widestLine = lineWidth
 				}
 				lineWidth = widthSinceLineBreak
 				lastLineBreak = [3]int{}
 			}
 		}
 
 		// Analyze break opportunities.
 		if boundaries&uniseg.MaskLine == uniseg.LineCanBreak {
 			lastLineBreak = pos
 			widthSinceLineBreak = 0
 		}
 		lastGraphemeBreak = pos
 
 		// Can we stop?
 		if len(t.lineStarts) > maxLines {
 			break
 		}
 	}
 
 	if lineWidth > t.widestLine {
 		t.widestLine = lineWidth
 	}
 }
 
 // truncateLines truncates the trailing lines of the [TextArea.lineStarts]
 // slice such that len(lineStarts) <= fromLine. If fromLine is negative, a value
 // of 0 is assumed. If it is greater than the length of lineStarts, nothing
 // happens.
 func (t *TextArea) truncateLines(fromLine int) {
 	if fromLine < 0 {
 		fromLine = 0
 	}
 	if fromLine < len(t.lineStarts) {
 		t.lineStarts = t.lineStarts[:fromLine]
 	}
 }
 
 // findCursor determines the cursor position if its "row" value is < 0
 // (=unknown) but only its span position ("pos" value) is known. If the cursor
 // position is already known (row >= 0), it can also be used to modify row and
 // column offsets such that the cursor is visible during the next call to
 // [TextArea.Draw], by setting "clamp" to true.
 //
 // To determine the cursor position, "startRow" helps reduce processing time by
 // indicating the lowest row in which searching should start. Set this to 0 if
 // you don't have any information where the cursor might be (but know that this
 // is expensive for long texts).
 //
 // The cursor's desired column will be set to its actual column.
 func (t *TextArea) findCursor(clamp bool, startRow int) {
 	defer func() {
 		t.cursor.column = t.cursor.actualColumn
 	}()
 
 	if !clamp && t.cursor.row >= 0 || t.lastWidth <= 0 {
 		return // Nothing to do.
 	}
 
 	// Clamp to viewport.
 	if clamp && t.cursor.row >= 0 {
 		cursorRow := t.cursor.row
 		if t.wrap && t.cursor.actualColumn >= t.lastWidth {
 			cursorRow++ // A row can push the cursor just outside the viewport. It will wrap onto the next line.
 		}
 		if cursorRow < t.rowOffset {
 			// We're above the viewport.
 			t.rowOffset = cursorRow
 		} else if cursorRow >= t.rowOffset+t.lastHeight {
 			// We're below the viewport.
 			t.rowOffset = cursorRow - t.lastHeight + 1
 			if t.rowOffset >= len(t.lineStarts) {
 				t.extendLines(t.lastWidth, t.rowOffset)
 				if t.rowOffset >= len(t.lineStarts) {
 					t.rowOffset = len(t.lineStarts) - 1
 					if t.rowOffset < 0 {
 						t.rowOffset = 0
 					}
 				}
 			}
 		}
 		if !t.wrap {
 			if t.cursor.actualColumn < t.columnOffset+t.minCursorPrefix {
 				// We're left of the viewport.
 				t.columnOffset = t.cursor.actualColumn - t.minCursorPrefix
 				if t.columnOffset < 0 {
 					t.columnOffset = 0
 				}
 			} else if t.cursor.actualColumn >= t.columnOffset+t.lastWidth-t.minCursorSuffix {
 				// We're right of the viewport.
 				t.columnOffset = t.cursor.actualColumn - t.lastWidth + t.minCursorSuffix
 				if t.columnOffset >= t.widestLine {
 					t.columnOffset = t.widestLine - 1
 					if t.columnOffset < 0 {
 						t.columnOffset = 0
 					}
 				}
 			}
 		}
 		return
 	}
 
 	// The screen position of the cursor is unknown. Find it. This can be
 	// expensive. First, find the row.
 	row := startRow
 	if row < 0 {
 		row = 0
 	}
 RowLoop:
 	for {
 		// Examine the current row.
 		if row+1 >= len(t.lineStarts) {
 			t.extendLines(t.lastWidth, row+1)
 		}
 		if row >= len(t.lineStarts) {
 			t.cursor.row, t.cursor.actualColumn, t.cursor.pos = row, 0, [3]int{1, 0, -1}
 			break // It's the end of the text.
 		}
 
 		// Check this row's spans to see if the cursor is in this row.
 		pos := t.lineStarts[row]
 		for pos[0] != 1 {
 			if row+1 >= len(t.lineStarts) {
 				break // It's the last row so the cursor must be in this row.
 			}
 			if t.cursor.pos[0] == pos[0] {
 				// The cursor is in this span.
 				if t.lineStarts[row+1][0] == pos[0] {
 					// The next row starts with the same span.
 					if t.cursor.pos[1] >= t.lineStarts[row+1][1] {
 						// The cursor is not in this row.
 						row++
 						continue RowLoop
 					} else {
 						// The cursor is in this row.
 						break
 					}
 				} else {
 					// The next row starts with a different span. The cursor
 					// must be in this row.
 					break
 				}
 			} else {
 				// The cursor is in a different span.
 				if t.lineStarts[row+1][0] == pos[0] {
 					// The next row starts with the same span. This row is
 					// irrelevant.
 					row++
 					continue RowLoop
 				} else {
 					// The next row starts with a different span. Move towards it.
 					pos = [3]int{t.spans[pos[0]].next, 0, -1}
 				}
 			}
 		}
 
 		// Try to find the screen position in this row.
 		pos = t.lineStarts[row]
 		endPos := pos
 		column := 0
 		var text string
 		for {
 			if pos[0] == 1 || t.cursor.pos[0] == pos[0] && t.cursor.pos[1] == pos[1] {
 				// We found the position. We're done.
 				t.cursor.row, t.cursor.actualColumn, t.cursor.pos = row, column, pos
 				break RowLoop
 			}
 			var clusterWidth int
 			_, text, _, clusterWidth, pos, endPos = t.step(text, pos, endPos)
 			if row+1 < len(t.lineStarts) && t.lineStarts[row+1] == pos {
 				// We reached the end of the line. Go to the next one.
 				row++
 				continue RowLoop
 			}
 			column += clusterWidth
 		}
 	}
 
 	if clamp && t.cursor.row >= 0 {
 		// We know the position now. Adapt offsets.
 		t.findCursor(true, startRow)
 	}
 }
 
 // setTransform sets the transform function to be used when drawing the text.
 // This function is called for each grapheme cluster and can be used to modify
 // the cluster, the cluster's screen width, and the cluster's boundaries. The
 // function is called with the original cluster, the rest of the text, the
 // original cluster's width, and the original cluster's boundaries. The function
 // must return the new cluster, the new width, and the new boundaries. This only
 // affects the drawing of the text, not the text content itself. The boundaries
 // values correspond to the values returned by
 // [github.com/rivo/uniseg.StepString].
 func (t *TextArea) setTransform(transform func(cluster, rest string, boundaries int) (newCluster string, newBoundaries int)) {
 	t.transform = transform
 }
 
 // step is similar to [github.com/rivo/uniseg.StepString] but it iterates over
 // the piece chain, starting with "pos", a span position plus state (which may
 // be -1 for the start of the text). The returned "boundaries" value is the same
 // value returned by [github.com/rivo/uniseg.StepString], "width" is the screen
 // width of the grapheme. The "pos" and "endPos" positions refer to the start
 // and the end of the "text" string, respectively. For the first call, text may
 // be empty and pos/endPos may be the same. For consecutive calls, provide
 // "rest" as the text and "newPos" and "newEndPos" as the new positions/states.
 // An empty "rest" string indicates the end of the text. The "endPos" state is
 // irrelevant.
 func (t *TextArea) step(text string, pos, endPos [3]int) (cluster, rest string, boundaries, width int, newPos, newEndPos [3]int) {
 	if pos[0] == 1 {
 		return // We're already past the end.
 	}
 
 	// We want to make sure we have a text at least the size of a grapheme
 	// cluster.
 	span := t.spans[pos[0]]
 	if len(text) < maxGraphemeClusterSize &&
 		(span.length < 0 && -span.length-pos[1] >= maxGraphemeClusterSize ||
 			span.length > 0 && t.spans[pos[0]].length-pos[1] >= maxGraphemeClusterSize) {
 		// We can use a substring of one span.
 		if span.length < 0 {
 			text = t.initialText[span.offset+pos[1] : span.offset-span.length]
 		} else {
 			text = t.editText.String()[span.offset+pos[1] : span.offset+span.length]
 		}
 		endPos = [3]int{span.next, 0, -1}
 	} else {
 		// We have to compose the text from multiple spans.
 		for len(text) < maxGraphemeClusterSize && endPos[0] != 1 {
 			endSpan := t.spans[endPos[0]]
 			var moreText string
 			if endSpan.length < 0 {
 				moreText = t.initialText[endSpan.offset+endPos[1] : endSpan.offset-endSpan.length]
 			} else {
 				moreText = t.editText.String()[endSpan.offset+endPos[1] : endSpan.offset+endSpan.length]
 			}
 			if len(moreText) > maxGraphemeClusterSize {
 				moreText = moreText[:maxGraphemeClusterSize]
 			}
 			text += moreText
 			endPos[1] += len(moreText)
 			if endPos[1] >= endSpan.length {
 				endPos[0], endPos[1] = endSpan.next, 0
 			}
 		}
 	}
 
 	// Run the grapheme cluster iterator.
 	cluster, text, boundaries, pos[2] = uniseg.StepString(text, pos[2])
 	pos[1] += len(cluster)
 	for pos[0] != 1 && (span.length < 0 && pos[1] >= -span.length || span.length >= 0 && pos[1] >= span.length) {
 		pos[0] = span.next
 		if span.length < 0 {
 			pos[1] += span.length
 		} else {
 			pos[1] -= span.length
 		}
 		span = t.spans[pos[0]]
 	}
 
 	if t.transform != nil {
 		cluster, boundaries = t.transform(cluster, text, boundaries)
 	}
 
 	if cluster == "\t" {
 		width = TabSize
 	} else {
 		width = boundaries >> uniseg.ShiftWidth
 	}
 
 	return cluster, text, boundaries, width, pos, endPos
 }
 
 // moveCursor sets the cursor's screen position and span position for the given
 // row and column which are screen space coordinates relative to the top-left
 // corner of the text area's full text (visible or not). The column value may be
 // negative, in which case, the cursor will be placed at the end of the line.
 // The cursor's actual position will be aligned with a grapheme cluster
 // boundary. The next call to [TextArea.Draw] will attempt to keep the cursor in
 // the viewport.
 func (t *TextArea) moveCursor(row, column int) {
 	// Are we within the range of rows?
 	if len(t.lineStarts) <= row {
 		// No. Extent the line buffer.
 		t.extendLines(t.lastWidth, row)
 	}
 	if len(t.lineStarts) == 0 {
 		return // No lines. Nothing to do.
 	}
 	if row < 0 {
 		// We're at the start of the text.
 		row = 0
 		column = 0
 	} else if row >= len(t.lineStarts) {
 		// We're already past the end.
 		row = len(t.lineStarts) - 1
 		column = -1
 	}
 
 	// Iterate through this row until we find the position.
 	t.cursor.row, t.cursor.actualColumn = row, 0
 	if t.wrap {
 		t.cursor.actualColumn = 0
 	}
 	pos := t.lineStarts[row]
 	endPos := pos
 	var text string
 	for pos[0] != 1 {
 		var clusterWidth int
 		oldPos := pos // We may have to revert to this position.
 		_, text, _, clusterWidth, pos, endPos = t.step(text, pos, endPos)
 		if len(t.lineStarts) > row+1 && pos == t.lineStarts[row+1] || // We've reached the end of the line.
 			column >= 0 && t.cursor.actualColumn+clusterWidth > column { // We're past the requested column.
 			pos = oldPos
 			break
 		}
 		t.cursor.actualColumn += clusterWidth
 	}
 
 	if column < 0 {
 		t.cursor.column = t.cursor.actualColumn
 	} else {
 		t.cursor.column = column
 	}
 	t.cursor.pos = pos
 	t.findCursor(true, row)
 }
 
 // moveWordRight moves the cursor to the end of the current or next word. If
 // after is set to true, the cursor will be placed after the word. If false, the
 // cursor will be placed on the last character of the word. If clamp is set to
 // true, the cursor will be visible during the next call to [TextArea.Draw].
 func (t *TextArea) moveWordRight(after, clamp bool) {
 	// Because we rely on clampToCursor to calculate the new screen position,
 	// this is an expensive operation for large texts.
 	pos := t.cursor.pos
 	endPos := pos
 	var (
 		cluster, text string
 		inWord        bool
 	)
 	for pos[0] != 0 {
 		var boundaries int
 		oldPos := pos
 		cluster, text, boundaries, _, pos, endPos = t.step(text, pos, endPos)
 		if oldPos == t.cursor.pos {
 			continue // Skip the first character.
 		}
 		firstRune, _ := utf8.DecodeRuneInString(cluster)
 		if !unicode.IsSpace(firstRune) && !unicode.IsPunct(firstRune) {
 			inWord = true
 		}
 		if inWord && boundaries&uniseg.MaskWord != 0 {
 			if !after {
 				pos = oldPos
 			}
 			break
 		}
 	}
 	startRow := t.cursor.row
 	t.cursor.row, t.cursor.column, t.cursor.actualColumn = -1, 0, 0
 	t.cursor.pos = pos
 	t.findCursor(clamp, startRow)
 }
 
 // moveWordLeft moves the cursor to the beginning of the current or previous
 // word. If clamp is true, the cursor will be visible during the next call to
 // [TextArea.Draw].
 func (t *TextArea) moveWordLeft(clamp bool) {
 	// We go back row by row, trying to find the last word boundary before the
 	// cursor.
 	row := t.cursor.row
 	if row+1 < len(t.lineStarts) {
 		t.extendLines(t.lastWidth, row+1)
 	}
 	if row >= len(t.lineStarts) {
 		row = len(t.lineStarts) - 1
 	}
 	for row >= 0 {
 		pos := t.lineStarts[row]
 		endPos := pos
 		var lastWordBoundary [3]int
 		var (
 			cluster, text string
 			inWord        bool
 			boundaries    int
 		)
 		for pos[0] != 1 && pos != t.cursor.pos {
 			oldBoundaries := boundaries
 			oldPos := pos
 			cluster, text, boundaries, _, pos, endPos = t.step(text, pos, endPos)
 			firstRune, _ := utf8.DecodeRuneInString(cluster)
 			wordRune := !unicode.IsSpace(firstRune) && !unicode.IsPunct(firstRune)
 			if oldBoundaries&uniseg.MaskWord != 0 {
 				if pos != t.cursor.pos && !inWord && wordRune {
 					// A boundary transitioning from a space/punctuation word to
 					// a letter word.
 					lastWordBoundary = oldPos
 				}
 				inWord = false
 			}
 			if wordRune {
 				inWord = true
 			}
 		}
 		if lastWordBoundary[0] != 0 {
 			// We found something.
 			t.cursor.pos = lastWordBoundary
 			break
 		}
 		row--
 	}
 	if row < 0 {
 		// We didn't find anything. We're at the start of the text.
 		t.cursor.pos = [3]int{t.spans[0].next, 0, -1}
 		row = 0
 	}
 	t.cursor.row, t.cursor.column, t.cursor.actualColumn = -1, 0, 0
 	t.findCursor(clamp, row)
 }
 
 // deleteLine deletes all characters between the last newline before the cursor
 // and the next newline after the cursor (inclusive).
 func (t *TextArea) deleteLine() {
 	// We go back row by row, trying to find the last mandatory line break
 	// before the cursor.
 	startRow := t.cursor.row
 	if t.cursor.actualColumn == 0 && t.cursor.pos[0] == 1 {
 		startRow-- // If we're at the very end, delete the row before.
 	}
 	if startRow+1 < len(t.lineStarts) {
 		t.extendLines(t.lastWidth, startRow+1)
 	}
 	if len(t.lineStarts) == 0 {
 		return // Nothing to delete.
 	}
 	if startRow >= len(t.lineStarts) {
 		startRow = len(t.lineStarts) - 1
 	}
 	for startRow >= 0 {
 		// What's the last rune before the start of the line?
 		pos := t.lineStarts[startRow]
 		span := t.spans[pos[0]]
 		var text string
 		if pos[1] > 0 {
 			// Extract text from this span.
 			if span.length < 0 {
 				text = t.initialText
 			} else {
 				text = t.editText.String()
 			}
 			text = text[:span.offset+pos[1]]
 		} else {
 			// Extract text from the previous span.
 			if span.previous != 0 {
 				span = t.spans[span.previous]
 				if span.length < 0 {
 					text = t.initialText[:span.offset-span.length]
 				} else {
 					text = t.editText.String()[:span.offset+span.length]
 				}
 			}
 		}
 		if uniseg.HasTrailingLineBreakInString(text) {
 			// The row before this one ends with a mandatory line break. This is
 			// the first line we will delete.
 			break
 		}
 		startRow--
 	}
 	if startRow < 0 {
 		// We didn't find anything. It'll be the first line.
 		startRow = 0
 	}
 
 	// Find the next line break after the cursor.
 	pos := t.cursor.pos
 	endPos := pos
 	var cluster, text string
 	for pos[0] != 1 {
 		cluster, text, _, _, pos, endPos = t.step(text, pos, endPos)
 		if uniseg.HasTrailingLineBreakInString(cluster) {
 			break
 		}
 	}
 
 	// Delete the text.
 	t.cursor.pos = t.replace(t.lineStarts[startRow], pos, "", false)
 	t.cursor.row = -1
 	t.truncateLines(startRow)
 	t.findCursor(true, startRow)
 }
 
 // getSelection returns the current selection as span locations where the first
 // returned location is always before or the same as the second returned
 // location. This assumes that the cursor and selection positions are known. The
 // third return value is the starting row of the selection.
 func (t *TextArea) getSelection() ([3]int, [3]int, int) {
 	from := t.selectionStart.pos
 	to := t.cursor.pos
 	row := t.selectionStart.row
 	if t.cursor.row < t.selectionStart.row ||
 		(t.cursor.row == t.selectionStart.row && t.cursor.actualColumn < t.selectionStart.actualColumn) {
 		from, to = to, from
 		row = t.cursor.row
 	}
 	return from, to, row
 }
 
 // getSelectedText returns the text of the current selection.
 func (t *TextArea) getSelectedText() string {
 	var text strings.Builder
 
 	from, to, _ := t.getSelection()
 	for from[0] != to[0] {
 		span := t.spans[from[0]]
 		if span.length < 0 {
 			text.WriteString(t.initialText[span.offset+from[1] : span.offset-span.length])
 		} else {
 			text.WriteString(t.editText.String()[span.offset+from[1] : span.offset+span.length])
 		}
 		from[0], from[1] = span.next, 0
 	}
 	if from[0] != 1 && from[1] < to[1] {
 		span := t.spans[from[0]]
 		if span.length < 0 {
 			text.WriteString(t.initialText[span.offset+from[1] : span.offset+to[1]])
 		} else {
 			text.WriteString(t.editText.String()[span.offset+from[1] : span.offset+to[1]])
 		}
 	}
 
 	return text.String()
 }
 
 // InputHandler returns the handler for this primitive.
 func (t *TextArea) InputHandler() func(event *tcell.EventKey, setFocus func(p Primitive)) {
 	return t.WrapInputHandler(func(event *tcell.EventKey, setFocus func(p Primitive)) {
 		if t.disabled {
 			return
 		}
 
 		// All actions except a few specific ones are "other" actions.
 		newLastAction := taActionOther
 		defer func() {
 			t.lastAction = newLastAction
 		}()
 
 		// Trigger a "moved" event if requested.
 		if t.moved != nil {
 			selectionStart, cursor := t.selectionStart, t.cursor
 			defer func() {
 				if selectionStart != t.selectionStart || cursor != t.cursor {
 					t.moved()
 				}
 			}()
 		}
 
 		// Process the different key events.
 		switch key := event.Key(); key {
 		case tcell.KeyLeft: // Move one grapheme cluster to the left.
 			if event.Modifiers()&tcell.ModAlt == 0 {
 				// Regular movement.
 				if event.Modifiers()&tcell.ModShift == 0 && t.selectionStart.pos != t.cursor.pos {
 					// Move to the start of the selection.
 					if t.selectionStart.row < t.cursor.row || (t.selectionStart.row == t.cursor.row && t.selectionStart.actualColumn < t.cursor.actualColumn) {
 						t.cursor = t.selectionStart
 					}
 					t.findCursor(true, t.cursor.row)
 				} else if event.Modifiers()&tcell.ModMeta != 0 || event.Modifiers()&tcell.ModCtrl != 0 {
 					// This captures Ctrl-Left on some systems.
 					t.moveWordLeft(event.Modifiers()&tcell.ModShift != 0)
 				} else if t.cursor.actualColumn == 0 {
 					// Move to the end of the previous row.
 					if t.cursor.row > 0 {
 						t.moveCursor(t.cursor.row-1, -1)
 					}
 				} else {
 					// Move one grapheme cluster to the left.
 					t.moveCursor(t.cursor.row, t.cursor.actualColumn-1)
 				}
 				if event.Modifiers()&tcell.ModShift == 0 {
 					t.selectionStart = t.cursor
 				}
 			} else if !t.wrap { // This doesn't work on all terminals.
 				// Just scroll.
 				t.columnOffset--
 				if t.columnOffset < 0 {
 					t.columnOffset = 0
 				}
 			}
 		case tcell.KeyRight: // Move one grapheme cluster to the right.
 			if event.Modifiers()&tcell.ModAlt == 0 {
 				// Regular movement.
 				if event.Modifiers()&tcell.ModShift == 0 && t.selectionStart.pos != t.cursor.pos {
 					// Move to the end of the selection.
 					if t.selectionStart.row > t.cursor.row || (t.selectionStart.row == t.cursor.row && t.selectionStart.actualColumn > t.cursor.actualColumn) {
 						t.cursor = t.selectionStart
 					}
 					t.findCursor(true, t.cursor.row)
 				} else if t.cursor.pos[0] != 1 {
 					if event.Modifiers()&tcell.ModMeta != 0 || event.Modifiers()&tcell.ModCtrl != 0 {
 						// This captures Ctrl-Right on some systems.
 						t.moveWordRight(event.Modifiers()&tcell.ModShift != 0, true)
 					} else {
 						// Move one grapheme cluster to the right.
 						var clusterWidth int
 						_, _, _, clusterWidth, t.cursor.pos, _ = t.step("", t.cursor.pos, t.cursor.pos)
 						if len(t.lineStarts) <= t.cursor.row+1 {
 							t.extendLines(t.lastWidth, t.cursor.row+1)
 						}
 						if t.cursor.row+1 < len(t.lineStarts) && t.lineStarts[t.cursor.row+1] == t.cursor.pos {
 							// We've reached the end of the line.
 							t.cursor.row++
 							t.cursor.actualColumn = 0
 							t.cursor.column = 0
 							t.findCursor(true, t.cursor.row)
 						} else {
 							// Move one character to the right.
 							t.moveCursor(t.cursor.row, t.cursor.actualColumn+clusterWidth)
 						}
 					}
 				}
 				if event.Modifiers()&tcell.ModShift == 0 {
 					t.selectionStart = t.cursor
 				}
 			} else if !t.wrap { // This doesn't work on all terminals.
 				// Just scroll.
 				t.columnOffset++
 				if t.columnOffset >= t.widestLine {
 					t.columnOffset = t.widestLine - 1
 					if t.columnOffset < 0 {
 						t.columnOffset = 0
 					}
 				}
 			}
 		case tcell.KeyDown: // Move one row down.
 			if event.Modifiers()&tcell.ModAlt == 0 {
 				// Regular movement.
 				column := t.cursor.column
 				t.moveCursor(t.cursor.row+1, t.cursor.column)
 				t.cursor.column = column
 				if event.Modifiers()&tcell.ModShift == 0 {
 					t.selectionStart = t.cursor
 				}
 			} else {
 				// Just scroll.
 				t.rowOffset++
 				if t.rowOffset >= len(t.lineStarts) {
 					t.extendLines(t.lastWidth, t.rowOffset)
 					if t.rowOffset >= len(t.lineStarts) {
 						t.rowOffset = len(t.lineStarts) - 1
 						if t.rowOffset < 0 {
 							t.rowOffset = 0
 						}
 					}
 				}
 			}
 		case tcell.KeyUp: // Move one row up.
 			if event.Modifiers()&tcell.ModAlt == 0 {
 				// Regular movement.
 				column := t.cursor.column
 				t.moveCursor(t.cursor.row-1, t.cursor.column)
 				t.cursor.column = column
 				if event.Modifiers()&tcell.ModShift == 0 {
 					t.selectionStart = t.cursor
 				}
 			} else {
 				// Just scroll.
 				t.rowOffset--
 				if t.rowOffset < 0 {
 					t.rowOffset = 0
 				}
 			}
 		case tcell.KeyHome, tcell.KeyCtrlA: // Move to the start of the line.
 			t.moveCursor(t.cursor.row, 0)
 			if event.Modifiers()&tcell.ModShift == 0 {
 				t.selectionStart = t.cursor
 			}
 		case tcell.KeyEnd, tcell.KeyCtrlE: // Move to the end of the line.
 			t.moveCursor(t.cursor.row, -1)
 			if event.Modifiers()&tcell.ModShift == 0 {
 				t.selectionStart = t.cursor
 			}
 		case tcell.KeyPgDn, tcell.KeyCtrlF: // Move one page down.
 			column := t.cursor.column
 			t.moveCursor(t.cursor.row+t.lastHeight, t.cursor.column)
 			t.cursor.column = column
 			if event.Modifiers()&tcell.ModShift == 0 {
 				t.selectionStart = t.cursor
 			}
 		case tcell.KeyPgUp, tcell.KeyCtrlB: // Move one page up.
 			column := t.cursor.column
 			t.moveCursor(t.cursor.row-t.lastHeight, t.cursor.column)
 			t.cursor.column = column
 			if event.Modifiers()&tcell.ModShift == 0 {
 				t.selectionStart = t.cursor
 			}
 		case tcell.KeyEnter: // Insert a newline.
 			from, to, row := t.getSelection()
 			t.cursor.pos = t.replace(from, to, NewLine, t.lastAction == taActionTypeSpace)
 			t.cursor.row = -1
 			t.truncateLines(row - 1)
 			t.findCursor(true, row)
 			t.selectionStart = t.cursor
 			newLastAction = taActionTypeSpace
 		case tcell.KeyTab: // Insert a tab character. It will be rendered as TabSize spaces.
 			// But forwarding takes precedence.
 			if t.finished != nil {
 				t.finished(key)
 				return
 			}
 
 			from, to, row := t.getSelection()
 			t.cursor.pos = t.replace(from, to, "\t", t.lastAction == taActionTypeSpace)
 			t.cursor.row = -1
 			t.truncateLines(row - 1)
 			t.findCursor(true, row)
 			t.selectionStart = t.cursor
 			newLastAction = taActionTypeSpace
 		case tcell.KeyBacktab, tcell.KeyEscape: // Only used in forms.
 			if t.finished != nil {
 				t.finished(key)
 				return
 			}
 		case tcell.KeyRune:
 			if event.Modifiers()&tcell.ModAlt > 0 {
 				// We accept some Alt- key combinations.
 				switch event.Rune() {
 				case 'f':
 					if event.Modifiers()&tcell.ModShift == 0 {
 						t.moveWordRight(false, true)
 						t.selectionStart = t.cursor
 					} else {
 						t.moveWordRight(true, true)
 					}
 				case 'b':
 					t.moveWordLeft(true)
 					if event.Modifiers()&tcell.ModShift == 0 {
 						t.selectionStart = t.cursor
 					}
 				}
 			} else {
 				// Other keys are simply accepted as regular characters.
 				r := event.Rune()
 				from, to, row := t.getSelection()
 				newLastAction = taActionTypeNonSpace
 				if unicode.IsSpace(r) {
 					newLastAction = taActionTypeSpace
 				}
 				t.cursor.pos = t.replace(from, to, string(r), newLastAction == t.lastAction || t.lastAction == taActionTypeNonSpace && newLastAction == taActionTypeSpace)
 				t.cursor.row = -1
 				t.truncateLines(row - 1)
 				t.findCursor(true, row)
 				t.selectionStart = t.cursor
 			}
 		case tcell.KeyBackspace, tcell.KeyBackspace2: // Delete backwards. tcell.KeyBackspace is the same as tcell.CtrlH.
 			from, to, row := t.getSelection()
 			if from != to {
 				// Simply delete the current selection.
 				t.cursor.pos = t.replace(from, to, "", false)
 				t.cursor.row = -1
 				t.truncateLines(row - 1)
 				t.findCursor(true, row)
 				t.selectionStart = t.cursor
 				break
 			}
 
 			beforeCursor := t.cursor
 			if event.Modifiers()&tcell.ModAlt == 0 {
 				// Move the cursor back by one grapheme cluster.
 				if t.cursor.actualColumn == 0 {
 					// Move to the end of the previous row.
 					if t.cursor.row > 0 {
 						t.moveCursor(t.cursor.row-1, -1)
 					}
 				} else {
 					// Move one grapheme cluster to the left.
 					t.moveCursor(t.cursor.row, t.cursor.actualColumn-1)
 				}
 				newLastAction = taActionBackspace
 			} else {
 				// Move the cursor back by one word.
 				t.moveWordLeft(false)
 			}
 
 			// Remove that last grapheme cluster.
 			if t.cursor.pos != beforeCursor.pos {
 				t.cursor, beforeCursor = beforeCursor, t.cursor                                                 // So we put the right position on the stack.
 				t.cursor.pos = t.replace(beforeCursor.pos, t.cursor.pos, "", t.lastAction == taActionBackspace) // Delete the character.
 				t.cursor.row = -1
 				t.truncateLines(beforeCursor.row - 1)
 				t.findCursor(true, beforeCursor.row-1)
 			}
 			t.selectionStart = t.cursor
 		case tcell.KeyDelete, tcell.KeyCtrlD: // Delete forward.
 			from, to, row := t.getSelection()
 			if from != to {
 				// Simply delete the current selection.
 				t.cursor.pos = t.replace(from, to, "", false)
 				t.cursor.row = -1
 				t.truncateLines(row - 1)
 				t.findCursor(true, row)
 				t.selectionStart = t.cursor
 				break
 			}
 
 			if t.cursor.pos[0] != 1 {
 				_, _, _, _, endPos, _ := t.step("", t.cursor.pos, t.cursor.pos)
 				t.cursor.pos = t.replace(t.cursor.pos, endPos, "", t.lastAction == taActionDelete) // Delete the character.
 				t.cursor.pos[2] = endPos[2]
 				t.truncateLines(t.cursor.row - 1)
 				t.findCursor(true, t.cursor.row)
 				newLastAction = taActionDelete
 			}
 			t.selectionStart = t.cursor
 		case tcell.KeyCtrlK: // Delete everything under and to the right of the cursor until before the next newline character.
 			pos := t.cursor.pos
 			endPos := pos
 			var cluster, text string
 			for pos[0] != 1 {
 				var boundaries int
 				oldPos := pos
 				cluster, text, boundaries, _, pos, endPos = t.step(text, pos, endPos)
 				if boundaries&uniseg.MaskLine == uniseg.LineMustBreak {
 					if uniseg.HasTrailingLineBreakInString(cluster) {
 						pos = oldPos
 					}
 					break
 				}
 			}
 			t.cursor.pos = t.replace(t.cursor.pos, pos, "", false)
 			row := t.cursor.row
 			t.cursor.row = -1
 			t.truncateLines(row - 1)
 			t.findCursor(true, row)
 			t.selectionStart = t.cursor
 		case tcell.KeyCtrlW: // Delete from the start of the current word to the left of the cursor.
 			pos := t.cursor.pos
 			t.moveWordLeft(true)
 			t.cursor.pos = t.replace(t.cursor.pos, pos, "", false)
 			row := t.cursor.row - 1
 			t.cursor.row = -1
 			t.truncateLines(row)
 			t.findCursor(true, row)
 			t.selectionStart = t.cursor
 		case tcell.KeyCtrlU: // Delete the current line.
 			t.deleteLine()
 			t.selectionStart = t.cursor
 		case tcell.KeyCtrlL: // Select everything.
 			t.selectionStart.row, t.selectionStart.column, t.selectionStart.actualColumn = 0, 0, 0
 			t.selectionStart.pos = [3]int{t.spans[0].next, 0, -1}
 			row := t.cursor.row
 			t.cursor.row = -1
 			t.cursor.pos = [3]int{1, 0, -1}
 			t.findCursor(false, row)
 		case tcell.KeyCtrlQ: // Copy to clipboard.
 			if t.cursor != t.selectionStart {
 				t.copyToClipboard(t.getSelectedText())
 				t.selectionStart = t.cursor
 			}
 		case tcell.KeyCtrlX: // Cut to clipboard.
 			if t.cursor != t.selectionStart {
 				t.copyToClipboard(t.getSelectedText())
 				from, to, row := t.getSelection()
 				t.cursor.pos = t.replace(from, to, "", false)
 				t.cursor.row = -1
 				t.truncateLines(row - 1)
 				t.findCursor(true, row)
 				t.selectionStart = t.cursor
 			}
 		case tcell.KeyCtrlV: // Paste from clipboard.
 			from, to, row := t.getSelection()
 			t.cursor.pos = t.replace(from, to, t.pasteFromClipboard(), false)
 			t.cursor.row = -1
 			t.truncateLines(row - 1)
 			t.findCursor(true, row)
 			t.selectionStart = t.cursor
 		case tcell.KeyCtrlZ: // Undo.
 			if t.nextUndo <= 0 {
 				break
 			}
 			for t.nextUndo > 0 {
 				t.nextUndo--
 				undo := t.undoStack[t.nextUndo]
 				t.spans[undo.originalBefore], t.spans[undo.before] = t.spans[undo.before], t.spans[undo.originalBefore]
 				t.spans[undo.originalAfter], t.spans[undo.after] = t.spans[undo.after], t.spans[undo.originalAfter]
 				t.cursor.pos, t.undoStack[t.nextUndo].pos = undo.pos, t.cursor.pos
 				t.length, t.undoStack[t.nextUndo].length = undo.length, t.length
 				if !undo.continuation {
 					break
 				}
 			}
 			t.cursor.row = -1
 			t.truncateLines(0) // This is why Undo is expensive for large texts. (t.lineStarts can get largely unusable after an undo.)
 			t.findCursor(true, 0)
 			t.selectionStart = t.cursor
 			if t.changed != nil {
 				defer t.changed()
 			}
 		case tcell.KeyCtrlY: // Redo.
 			if t.nextUndo >= len(t.undoStack) {
 				break
 			}
 			for t.nextUndo < len(t.undoStack) {
 				undo := t.undoStack[t.nextUndo]
 				t.spans[undo.originalBefore], t.spans[undo.before] = t.spans[undo.before], t.spans[undo.originalBefore]
 				t.spans[undo.originalAfter], t.spans[undo.after] = t.spans[undo.after], t.spans[undo.originalAfter]
 				t.cursor.pos, t.undoStack[t.nextUndo].pos = undo.pos, t.cursor.pos
 				t.length, t.undoStack[t.nextUndo].length = undo.length, t.length
 				t.nextUndo++
 				if t.nextUndo < len(t.undoStack) && !t.undoStack[t.nextUndo].continuation {
 					break
 				}
 			}
 			t.cursor.row = -1
 			t.truncateLines(0) // This is why Redo is expensive for large texts. (t.lineStarts can get largely unusable after an undo.)
 			t.findCursor(true, 0)
 			t.selectionStart = t.cursor
 			if t.changed != nil {
 				defer t.changed()
 			}
 		}
 	})
 }
 
 // MouseHandler returns the mouse handler for this primitive.
 func (t *TextArea) MouseHandler() func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
 	return t.WrapMouseHandler(func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
 		if t.disabled {
 			return false, nil
 		}
 
 		x, y := event.Position()
 		rectX, rectY, _, _ := t.GetInnerRect()
 		if !t.InRect(x, y) {
 			return false, nil
 		}
 
 		// Trigger a "moved" event at the end if requested.
 		if t.moved != nil {
 			selectionStart, cursor := t.selectionStart, t.cursor
 			defer func() {
 				if selectionStart != t.selectionStart || cursor != t.cursor {
 					t.moved()
 				}
 			}()
 		}
 
 		// Turn mouse coordinates into text coordinates.
 		labelWidth := t.labelWidth
 		if labelWidth == 0 && t.label != "" {
 			labelWidth = TaggedStringWidth(t.label)
 		}
 		column := x - rectX - labelWidth
 		row := y - rectY
 		if !t.wrap {
 			column += t.columnOffset
 		}
 		row += t.rowOffset
 
 		// Process mouse actions.
 		switch action {
 		case MouseLeftDown:
 			t.moveCursor(row, column)
 			if event.Modifiers()&tcell.ModShift == 0 {
 				t.selectionStart = t.cursor
 			}
 			setFocus(t)
 			consumed = true
 			capture = t
 			t.dragging = true
 		case MouseMove:
 			if !t.dragging {
 				break
 			}
 			t.moveCursor(row, column)
 			consumed = true
 		case MouseLeftUp:
 			t.moveCursor(row, column)
 			consumed = true
 			capture = nil
 			t.dragging = false
 		case MouseLeftDoubleClick: // Select word.
 			// Left down/up was already triggered so we are at the correct
 			// position.
 			t.moveWordLeft(false)
 			t.selectionStart = t.cursor
 			t.moveWordRight(true, false)
 			consumed = true
 		case MouseScrollUp:
 			if t.rowOffset > 0 {
 				t.rowOffset--
 			}
 			consumed = true
 		case MouseScrollDown:
 			t.rowOffset++
 			if t.rowOffset >= len(t.lineStarts) {
 				t.rowOffset = len(t.lineStarts) - 1
 				if t.rowOffset < 0 {
 					t.rowOffset = 0
 				}
 			}
 			consumed = true
 		case MouseScrollLeft:
 			if t.columnOffset > 0 {
 				t.columnOffset--
 			}
 			consumed = true
 		case MouseScrollRight:
 			t.columnOffset++
 			if t.columnOffset >= t.widestLine {
 				t.columnOffset = t.widestLine - 1
 				if t.columnOffset < 0 {
 					t.columnOffset = 0
 				}
 			}
 			consumed = true
 		}
 
 		return
 	})
 }
 
 // PasteHandler returns the handler for this primitive.
 func (t *TextArea) PasteHandler() func(pastedText string, setFocus func(p Primitive)) {
 	return t.WrapPasteHandler(func(pastedText string, setFocus func(p Primitive)) {
 		from, to, row := t.getSelection()
 		t.cursor.pos = t.replace(from, to, pastedText, false)
 		t.cursor.row = -1
 		t.truncateLines(row - 1)
 		t.findCursor(true, row)
 		t.selectionStart = t.cursor
 	})
 }