Class

GtkTextView

Description [src]

class Gtk.TextView : Gtk.Widget
  implements Gtk.Accessible, Gtk.AccessibleText, Gtk.Buildable, Gtk.ConstraintTarget, Gtk.Scrollable {
  /* No available fields */
}

A widget that displays the contents of a GtkTextBuffer.

An example GtkTextView

You may wish to begin by reading the conceptual overview, which gives an overview of all the objects and data types related to the text widget and how they work together.

Shortcuts and Gestures

GtkTextView supports the following keyboard shortcuts:

  • Shift+F10 or Menu opens the context menu.
  • Ctrl+Z undoes the last modification.
  • Ctrl+Y or Ctrl+Shift+Z redoes the last undone modification.

Additionally, the following signals have default keybindings:

Actions

GtkTextView defines a set of built-in actions:

  • clipboard.copy copies the contents to the clipboard.
  • clipboard.cut copies the contents to the clipboard and deletes it from the widget.
  • clipboard.paste inserts the contents of the clipboard into the widget.
  • menu.popup opens the context menu.
  • misc.insert-emoji opens the Emoji chooser.
  • selection.delete deletes the current selection.
  • selection.select-all selects all of the widgets content.
  • text.redo redoes the last change to the contents.
  • text.undo undoes the last change to the contents.

CSS nodes

textview.view
├── border.top
├── border.left
├── text
│   ╰── [selection]
├── border.right
├── border.bottom
╰── [window.popup]

GtkTextView has a main css node with name textview and style class .view, and subnodes for each of the border windows, and the main text area, with names border and text, respectively. The border nodes each get one of the style classes .left, .right, .top or .bottom.

A node representing the selection will appear below the text node.

If a context menu is opened, the window node will appear as a subnode of the main node.

Accessibility

GtkTextView uses the GTK_ACCESSIBLE_ROLE_TEXT_BOX role.

Hierarchy

hierarchy this GtkTextView implements_0 GtkAccessible this--implements_0 implements_1 GtkAccessibleText this--implements_1 implements_2 GtkBuildable this--implements_2 implements_3 GtkConstraintTarget this--implements_3 implements_4 GtkScrollable this--implements_4 ancestor_0 GtkWidget ancestor_0--this ancestor_1 GInitiallyUnowned ancestor_1--ancestor_0 ancestor_2 GObject ancestor_2--ancestor_1

Constructors

gtk_text_view_new

Creates a new GtkTextView.

gtk_text_view_new_with_buffer

Creates a new GtkTextView widget displaying the buffer buffer.

Instance methods

gtk_text_view_add_child_at_anchor

Adds a child widget in the text buffer, at the given anchor.

gtk_text_view_add_overlay

Adds child at a fixed coordinate in the GtkTextViews text window.

gtk_text_view_backward_display_line

Moves the given iter backward by one display (wrapped) line.

gtk_text_view_backward_display_line_start

Moves the given iter backward to the next display line start.

gtk_text_view_buffer_to_window_coords

Converts buffer coordinates to window coordinates.

gtk_text_view_forward_display_line

Moves the given iter forward by one display (wrapped) line.

gtk_text_view_forward_display_line_end

Moves the given iter forward to the next display line end.

gtk_text_view_get_accepts_tab

Returns whether pressing the Tab key inserts a tab characters.

gtk_text_view_get_bottom_margin

Gets the bottom margin for text in the text_view.

gtk_text_view_get_buffer

Returns the GtkTextBuffer being displayed by this text view.

gtk_text_view_get_cursor_locations

Determine the positions of the strong and weak cursors if the insertion point is at iter.

gtk_text_view_get_cursor_visible

Find out whether the cursor should be displayed.

gtk_text_view_get_editable

Returns the default editability of the GtkTextView.

gtk_text_view_get_extra_menu

Gets the menu model that gets added to the context menu or NULL if none has been set.

gtk_text_view_get_gutter

Gets a GtkWidget that has previously been set as gutter.

gtk_text_view_get_indent

Gets the default indentation of paragraphs in text_view.

gtk_text_view_get_input_hints

Gets the input-hints of the GtkTextView.

gtk_text_view_get_input_purpose

Gets the input-purpose of the GtkTextView.

gtk_text_view_get_iter_at_location

Retrieves the iterator at buffer coordinates x and y.

gtk_text_view_get_iter_at_position

Retrieves the iterator pointing to the character at buffer coordinates x and y.

gtk_text_view_get_iter_location

Gets a rectangle which roughly contains the character at iter.

gtk_text_view_get_justification

Gets the default justification of paragraphs in text_view.

gtk_text_view_get_left_margin

Gets the default left margin size of paragraphs in the text_view.

gtk_text_view_get_line_at_y

Gets the GtkTextIter at the start of the line containing the coordinate y.

gtk_text_view_get_line_yrange

Gets the y coordinate of the top of the line containing iter, and the height of the line.

gtk_text_view_get_ltr_context

Gets the PangoContext that is used for rendering LTR directed text layouts.

since: 4.4

gtk_text_view_get_monospace

Gets whether the GtkTextView uses monospace styling.

gtk_text_view_get_overwrite

Returns whether the GtkTextView is in overwrite mode or not.

gtk_text_view_get_pixels_above_lines

Gets the default number of pixels to put above paragraphs.

gtk_text_view_get_pixels_below_lines

Gets the default number of pixels to put below paragraphs.

gtk_text_view_get_pixels_inside_wrap

Gets the default number of pixels to put between wrapped lines inside a paragraph.

gtk_text_view_get_right_margin

Gets the default right margin for text in text_view.

gtk_text_view_get_rtl_context

Gets the PangoContext that is used for rendering RTL directed text layouts.

since: 4.4

gtk_text_view_get_tabs

Gets the default tabs for text_view.

gtk_text_view_get_top_margin

Gets the top margin for text in the text_view.

gtk_text_view_get_visible_offset

Gets the X,Y offset in buffer coordinates of the top-left corner of the textview’s text contents.

unstable since: 4.18

gtk_text_view_get_visible_rect

Fills visible_rect with the currently-visible region of the buffer, in buffer coordinates.

gtk_text_view_get_wrap_mode

Gets the line wrapping for the view.

gtk_text_view_im_context_filter_keypress

Allow the GtkTextView input method to internally handle key press and release events.

gtk_text_view_move_mark_onscreen

Moves a mark within the buffer so that it’s located within the currently-visible text area.

gtk_text_view_move_overlay

Updates the position of a child.

gtk_text_view_move_visually

Move the iterator a given number of characters visually, treating it as the strong cursor position.

gtk_text_view_place_cursor_onscreen

Moves the cursor to the currently visible region of the buffer.

gtk_text_view_remove

Removes a child widget from text_view.

gtk_text_view_reset_cursor_blink

Ensures that the cursor is shown.

gtk_text_view_reset_im_context

Reset the input method context of the text view if needed.

gtk_text_view_scroll_mark_onscreen

Scrolls text_view the minimum distance such that mark is contained within the visible area of the widget.

gtk_text_view_scroll_to_iter

Scrolls text_view so that iter is on the screen in the position indicated by xalign and yalign.

gtk_text_view_scroll_to_mark

Scrolls text_view so that mark is on the screen in the position indicated by xalign and yalign.

gtk_text_view_set_accepts_tab

Sets the behavior of the text widget when the Tab key is pressed.

gtk_text_view_set_bottom_margin

Sets the bottom margin for text in text_view.

gtk_text_view_set_buffer

Sets buffer as the buffer being displayed by text_view.

gtk_text_view_set_cursor_visible

Toggles whether the insertion point should be displayed.

gtk_text_view_set_editable

Sets the default editability of the GtkTextView.

gtk_text_view_set_extra_menu

Sets a menu model to add when constructing the context menu for text_view.

gtk_text_view_set_gutter

Places widget into the gutter specified by win.

gtk_text_view_set_indent

Sets the default indentation for paragraphs in text_view.

gtk_text_view_set_input_hints

Sets the input-hints of the GtkTextView.

gtk_text_view_set_input_purpose

Sets the input-purpose of the GtkTextView.

gtk_text_view_set_justification

Sets the default justification of text in text_view.

gtk_text_view_set_left_margin

Sets the default left margin for text in text_view.

gtk_text_view_set_monospace

Sets whether the GtkTextView should display text in monospace styling.

gtk_text_view_set_overwrite

Changes the GtkTextView overwrite mode.

gtk_text_view_set_pixels_above_lines

Sets the default number of blank pixels above paragraphs in text_view.

gtk_text_view_set_pixels_below_lines

Sets the default number of pixels of blank space to put below paragraphs in text_view.

gtk_text_view_set_pixels_inside_wrap

Sets the default number of pixels of blank space to leave between display/wrapped lines within a paragraph.

gtk_text_view_set_right_margin

Sets the default right margin for text in the text view.

gtk_text_view_set_tabs

Sets the default tab stops for paragraphs in text_view.

gtk_text_view_set_top_margin

Sets the top margin for text in text_view.

gtk_text_view_set_wrap_mode

Sets the line wrapping for the view.

gtk_text_view_starts_display_line

Determines whether iter is at the start of a display line.

gtk_text_view_window_to_buffer_coords

Converts coordinates on the window identified by win to buffer coordinates.

Methods inherited from GtkWidget (162)

Please see GtkWidget for a full list of methods.

Methods inherited from GObject (43)

Please see GObject for a full list of methods.

Methods inherited from GtkAccessible (19)
gtk_accessible_announce

Requests the user’s screen reader to announce the given message.

since: 4.14

gtk_accessible_get_accessible_parent

Retrieves the accessible parent for an accessible object.

since: 4.10

gtk_accessible_get_accessible_role

Retrieves the accessible role of an accessible object.

gtk_accessible_get_at_context

Retrieves the implementation for the given accessible object.

since: 4.10

gtk_accessible_get_bounds

Queries the coordinates and dimensions of this accessible.

since: 4.10

gtk_accessible_get_first_accessible_child

Retrieves the first accessible child of an accessible object.

since: 4.10

gtk_accessible_get_next_accessible_sibling

Retrieves the next accessible sibling of an accessible object.

since: 4.10

gtk_accessible_get_platform_state

Queries a platform state, such as focus.

since: 4.10

gtk_accessible_reset_property

Resets the accessible property to its default value.

gtk_accessible_reset_relation

Resets the accessible relation to its default value.

gtk_accessible_reset_state

Resets the accessible state to its default value.

gtk_accessible_set_accessible_parent

Sets the parent and sibling of an accessible object.

since: 4.10

gtk_accessible_update_next_accessible_sibling

Updates the next accessible sibling.

since: 4.10

gtk_accessible_update_property

Updates a list of accessible properties.

gtk_accessible_update_property_value

Updates an array of accessible properties.

gtk_accessible_update_relation

Updates a list of accessible relations.

gtk_accessible_update_relation_value

Updates an array of accessible relations.

gtk_accessible_update_state

Updates a list of accessible states.

gtk_accessible_update_state_value

Updates an array of accessible states.

Methods inherited from GtkAccessibleText (3)
gtk_accessible_text_update_caret_position

Updates the position of the caret.

since: 4.14

gtk_accessible_text_update_contents

Notifies assistive technologies of a change in contents.

since: 4.14

gtk_accessible_text_update_selection_bound

Updates the boundary of the selection.

since: 4.14

Methods inherited from GtkBuildable (1)
gtk_buildable_get_buildable_id

Gets the ID of the buildable object.

Methods inherited from GtkScrollable (9)
gtk_scrollable_get_border

Returns the size of a non-scrolling border around the outside of the scrollable.

gtk_scrollable_get_hadjustment

Retrieves the GtkAdjustment used for horizontal scrolling.

gtk_scrollable_get_hscroll_policy

Gets the horizontal GtkScrollablePolicy.

gtk_scrollable_get_vadjustment

Retrieves the GtkAdjustment used for vertical scrolling.

gtk_scrollable_get_vscroll_policy

Gets the vertical GtkScrollablePolicy.

gtk_scrollable_set_hadjustment

Sets the horizontal adjustment of the GtkScrollable.

gtk_scrollable_set_hscroll_policy

Sets the GtkScrollablePolicy.

gtk_scrollable_set_vadjustment

Sets the vertical adjustment of the GtkScrollable.

gtk_scrollable_set_vscroll_policy

Sets the GtkScrollablePolicy.

Properties

Gtk.TextView:accepts-tab

Whether Tab will result in a tab character being entered.

Gtk.TextView:bottom-margin

The bottom margin for text in the text view.

Gtk.TextView:buffer

The buffer which is displayed.

Gtk.TextView:cursor-visible

If the insertion cursor is shown.

Gtk.TextView:editable

Whether the text can be modified by the user.

Gtk.TextView:extra-menu

A menu model whose contents will be appended to the context menu.

Gtk.TextView:im-module

Which IM (input method) module should be used for this text_view.

Gtk.TextView:indent

Amount to indent the paragraph, in pixels.

Gtk.TextView:input-hints

Additional hints (beyond GtkTextView:input-purpose) that allow input methods to fine-tune their behaviour.

Gtk.TextView:input-purpose

The purpose of this text field.

Gtk.TextView:justification

Left, right, or center justification.

Gtk.TextView:left-margin

The default left margin for text in the text view.

Gtk.TextView:monospace

Whether text should be displayed in a monospace font.

Gtk.TextView:overwrite

Whether entered text overwrites existing contents.

Gtk.TextView:pixels-above-lines

Pixels of blank space above paragraphs.

Gtk.TextView:pixels-below-lines

Pixels of blank space below paragraphs.

Gtk.TextView:pixels-inside-wrap

Pixels of blank space between wrapped lines in a paragraph.

Gtk.TextView:right-margin

The default right margin for text in the text view.

Gtk.TextView:tabs

Custom tabs for this text.

Gtk.TextView:top-margin

The top margin for text in the text view.

Gtk.TextView:wrap-mode

Whether to wrap lines never, at word boundaries, or at character boundaries.

Properties inherited from GtkWidget (34)
Gtk.Widget:can-focus

Whether the widget or any of its descendents can accept the input focus.

Gtk.Widget:can-target

Whether the widget can receive pointer events.

Gtk.Widget:css-classes

A list of css classes applied to this widget.

Gtk.Widget:css-name

The name of this widget in the CSS tree.

Gtk.Widget:cursor

The cursor used by widget.

Gtk.Widget:focus-on-click

Whether the widget should grab focus when it is clicked with the mouse.

Gtk.Widget:focusable

Whether this widget itself will accept the input focus.

Gtk.Widget:halign

How to distribute horizontal space if widget gets extra space.

Gtk.Widget:has-default

Whether the widget is the default widget.

Gtk.Widget:has-focus

Whether the widget has the input focus.

Gtk.Widget:has-tooltip

Enables or disables the emission of the GtkWidget::query-tooltip signal on widget.

Gtk.Widget:height-request

Overrides for height request of the widget.

Gtk.Widget:hexpand

Whether to expand horizontally.

Gtk.Widget:hexpand-set

Whether to use the hexpand property.

Gtk.Widget:layout-manager

The GtkLayoutManager instance to use to compute the preferred size of the widget, and allocate its children.

Gtk.Widget:margin-bottom

Margin on bottom side of widget.

Gtk.Widget:margin-end

Margin on end of widget, horizontally.

Gtk.Widget:margin-start

Margin on start of widget, horizontally.

Gtk.Widget:margin-top

Margin on top side of widget.

Gtk.Widget:name

The name of the widget.

Gtk.Widget:opacity

The requested opacity of the widget.

Gtk.Widget:overflow

How content outside the widget’s content area is treated.

Gtk.Widget:parent

The parent widget of this widget.

Gtk.Widget:receives-default

Whether the widget will receive the default action when it is focused.

Gtk.Widget:root

The GtkRoot widget of the widget tree containing this widget.

Gtk.Widget:scale-factor

The scale factor of the widget.

Gtk.Widget:sensitive

Whether the widget responds to input.

Gtk.Widget:tooltip-markup

Sets the text of tooltip to be the given string, which is marked up with Pango markup.

Gtk.Widget:tooltip-text

Sets the text of tooltip to be the given string.

Gtk.Widget:valign

How to distribute vertical space if widget gets extra space.

Gtk.Widget:vexpand

Whether to expand vertically.

Gtk.Widget:vexpand-set

Whether to use the vexpand property.

Gtk.Widget:visible

Whether the widget is visible.

Gtk.Widget:width-request

Overrides for width request of the widget.

Properties inherited from GtkAccessible (1)
GtkAccessible:accessible-role

The accessible role of the given GtkAccessible implementation.

Properties inherited from GtkScrollable (4)
GtkScrollable:hadjustment

Horizontal GtkAdjustment of the scrollable widget.

GtkScrollable:hscroll-policy

Determines when horizontal scrolling should start.

GtkScrollable:vadjustment

Vertical GtkAdjustment of the scrollable widget.

GtkScrollable:vscroll-policy

Determines when vertical scrolling should start.

Signals

Gtk.TextView::backspace

Gets emitted when the user asks for it.

Gtk.TextView::copy-clipboard

Gets emitted to copy the selection to the clipboard.

Gtk.TextView::cut-clipboard

Gets emitted to cut the selection to the clipboard.

Gtk.TextView::delete-from-cursor

Gets emitted when the user initiates a text deletion.

Gtk.TextView::extend-selection

Emitted when the selection needs to be extended at location.

Gtk.TextView::insert-at-cursor

Gets emitted when the user initiates the insertion of a fixed string at the cursor.

Gtk.TextView::insert-emoji

Gets emitted to present the Emoji chooser for the text_view.

Gtk.TextView::move-cursor

Gets emitted when the user initiates a cursor movement.

Gtk.TextView::move-viewport

Gets emitted to move the viewport.

Gtk.TextView::paste-clipboard

Gets emitted to paste the contents of the clipboard into the text view.

Gtk.TextView::preedit-changed

Emitted when preedit text of the active IM changes.

Gtk.TextView::select-all

Gets emitted to select or unselect the complete contents of the text view.

Gtk.TextView::set-anchor

Gets emitted when the user initiates settings the “anchor” mark.

Gtk.TextView::toggle-cursor-visible

Gets emitted to toggle the cursor-visible property.

Gtk.TextView::toggle-overwrite

Gets emitted to toggle the overwrite mode of the text view.

Signals inherited from GtkWidget (13)
GtkWidget::destroy

Signals that all holders of a reference to the widget should release the reference that they hold.

GtkWidget::direction-changed

Emitted when the text direction of a widget changes.

GtkWidget::hide

Emitted when widget is hidden.

GtkWidget::keynav-failed

Emitted if keyboard navigation fails.

GtkWidget::map

Emitted when widget is going to be mapped.

GtkWidget::mnemonic-activate

Emitted when a widget is activated via a mnemonic.

GtkWidget::move-focus

Emitted when the focus is moved.

GtkWidget::query-tooltip

Emitted when the widget’s tooltip is about to be shown.

GtkWidget::realize

Emitted when widget is associated with a GdkSurface.

GtkWidget::show

Emitted when widget is shown.

GtkWidget::state-flags-changed

Emitted when the widget state changes.

GtkWidget::unmap

Emitted when widget is going to be unmapped.

GtkWidget::unrealize

Emitted when the GdkSurface associated with widget is destroyed.

Signals inherited from GObject (1)
GObject::notify

The notify signal is emitted on an object when one of its properties has its value set through g_object_set_property(), g_object_set(), et al.

Class structure

struct GtkTextViewClass {
  GtkWidgetClass parent_class;
  void (* move_cursor) (
    GtkTextView* text_view,
    GtkMovementStep step,
    int count,
    gboolean extend_selection
  );
  void (* set_anchor) (
    GtkTextView* text_view
  );
  void (* insert_at_cursor) (
    GtkTextView* text_view,
    const char* str
  );
  void (* delete_from_cursor) (
    GtkTextView* text_view,
    GtkDeleteType type,
    int count
  );
  void (* backspace) (
    GtkTextView* text_view
  );
  void (* cut_clipboard) (
    GtkTextView* text_view
  );
  void (* copy_clipboard) (
    GtkTextView* text_view
  );
  void (* paste_clipboard) (
    GtkTextView* text_view
  );
  void (* toggle_overwrite) (
    GtkTextView* text_view
  );
  GtkTextBuffer* (* create_buffer) (
    GtkTextView* text_view
  );
  void (* snapshot_layer) (
    GtkTextView* text_view,
    GtkTextViewLayer layer,
    GtkSnapshot* snapshot
  );
  gboolean (* extend_selection) (
    GtkTextView* text_view,
    GtkTextExtendSelection granularity,
    const GtkTextIter* location,
    GtkTextIter* start,
    GtkTextIter* end
  );
  void (* insert_emoji) (
    GtkTextView* text_view
  );
  
}

No description available.

Class members
parent_class: GtkWidgetClass

The object class structure needs to be the first.

move_cursor: void (* move_cursor) ( GtkTextView* text_view, GtkMovementStep step, int count, gboolean extend_selection )

The class handler for the GtkTextView::move-cursor keybinding signal.

set_anchor: void (* set_anchor) ( GtkTextView* text_view )

The class handler for the GtkTextView::set-anchor keybinding signal.

insert_at_cursor: void (* insert_at_cursor) ( GtkTextView* text_view, const char* str )

The class handler for the GtkTextView::insert-at-cursor keybinding signal.

delete_from_cursor: void (* delete_from_cursor) ( GtkTextView* text_view, GtkDeleteType type, int count )

The class handler for the GtkTextView::delete-from-cursor keybinding signal.

backspace: void (* backspace) ( GtkTextView* text_view )

The class handler for the GtkTextView::backspace keybinding signal.

cut_clipboard: void (* cut_clipboard) ( GtkTextView* text_view )

The class handler for the GtkTextView::cut-clipboard keybinding signal.

copy_clipboard: void (* copy_clipboard) ( GtkTextView* text_view )

The class handler for the GtkTextView::copy-clipboard keybinding signal.

paste_clipboard: void (* paste_clipboard) ( GtkTextView* text_view )

The class handler for the GtkTextView::paste-clipboard keybinding signal.

toggle_overwrite: void (* toggle_overwrite) ( GtkTextView* text_view )

The class handler for the GtkTextView::toggle-overwrite keybinding signal.

create_buffer: GtkTextBuffer* (* create_buffer) ( GtkTextView* text_view )

The create_buffer vfunc is called to create a GtkTextBuffer for the text view. The default implementation is to just call gtk_text_buffer_new().

snapshot_layer: void (* snapshot_layer) ( GtkTextView* text_view, GtkTextViewLayer layer, GtkSnapshot* snapshot )

The snapshot_layer vfunc is called before and after the text view is drawing its own text. Applications can override this vfunc in a subclass to draw customized content underneath or above the text. In the GTK_TEXT_VIEW_LAYER_BELOW_TEXT and GTK_TEXT_VIEW_LAYER_ABOVE_TEXT layers the drawing is done in the buffer coordinate space.

extend_selection: gboolean (* extend_selection) ( GtkTextView* text_view, GtkTextExtendSelection granularity, const GtkTextIter* location, GtkTextIter* start, GtkTextIter* end )

The class handler for the GtkTextView::extend-selection signal.

insert_emoji: void (* insert_emoji) ( GtkTextView* text_view )

The class handler for the GtkTextView::insert-emoji signal.

Virtual methods

Gtk.TextViewClass.backspace

The class handler for the GtkTextView::backspace keybinding signal.

Gtk.TextViewClass.copy_clipboard

The class handler for the GtkTextView::copy-clipboard keybinding signal.

Gtk.TextViewClass.create_buffer

The create_buffer vfunc is called to create a GtkTextBuffer for the text view. The default implementation is to just call gtk_text_buffer_new().

Gtk.TextViewClass.cut_clipboard

The class handler for the GtkTextView::cut-clipboard keybinding signal.

Gtk.TextViewClass.delete_from_cursor

The class handler for the GtkTextView::delete-from-cursor keybinding signal.

Gtk.TextViewClass.extend_selection

The class handler for the GtkTextView::extend-selection signal.

Gtk.TextViewClass.insert_at_cursor

The class handler for the GtkTextView::insert-at-cursor keybinding signal.

Gtk.TextViewClass.insert_emoji

The class handler for the GtkTextView::insert-emoji signal.

Gtk.TextViewClass.move_cursor

The class handler for the GtkTextView::move-cursor keybinding signal.

Gtk.TextViewClass.paste_clipboard

The class handler for the GtkTextView::paste-clipboard keybinding signal.

Gtk.TextViewClass.set_anchor

The class handler for the GtkTextView::set-anchor keybinding signal.

Gtk.TextViewClass.snapshot_layer

The snapshot_layer vfunc is called before and after the text view is drawing its own text. Applications can override this vfunc in a subclass to draw customized content underneath or above the text. In the GTK_TEXT_VIEW_LAYER_BELOW_TEXT and GTK_TEXT_VIEW_LAYER_ABOVE_TEXT layers the drawing is done in the buffer coordinate space.

Gtk.TextViewClass.toggle_overwrite

The class handler for the GtkTextView::toggle-overwrite keybinding signal.