GtkWidget introduces style properties - these are basically object properties that are stored not on the object, but in the style object associated to the widget. Style properties are set in resource files. This mechanism is used for configuring such things as the location of the scrollbar arrows through the theme, giving theme authors more control over the look of applications without the need to write a theme engine in C.

Use gtk_widget_class_install_style_property() to install style properties for a widget class, gtk_widget_class_find_style_property() or gtk_widget_class_list_style_properties() to get information about existing style properties and gtk_widget_style_get_property(), gtk_widget_style_get() or gtk_widget_style_get_valist() to obtain the value of a style property.

GtkWidget as GtkBuildable

The GtkWidget implementation of the GtkBuildable interface supports a custom <accelerator> element, which has attributes named key, modifiers and signal and allows to specify accelerators.

1
2
3

<object class="GtkButton">
  <accelerator key="q" modifiers="GDK_CONTROL_MASK" signal="clicked"/>
</object>

In addition to accelerators, GtkWidget also support a custom <accessible> element, which supports actions and relations. Properties on the accessible implementation of an object can be set by accessing the internal child "accessible" of a GtkWidget.

1
2
3
4
5
6
7
8
9
10
11
12
13
14

<object class="GtkButton" id="label1"/>
  <property name="label">I am a Label for a Button</property>
</object>
<object class="GtkButton" id="button1">
  <accessibility>
    <action action_name="click" translatable="yes">Click the button.</action>
    <relation target="label1" type="labelled-by"/>
  </accessibility>
  <child internal-child="accessible">
    <object class="AtkObject" id="a11y-button1">
      <property name="AtkObject::name">Clickable Button</property>
    </object>
  </child>
</object>

GtkWidget

typedef struct {
  /* The style for the widget. The style contains the
   *  colors the widget should be drawn in for each state
   *  along with graphics contexts used to draw with and
   *  the font to use for text.
   */
  GtkStyle *GSEAL (style);
  
  /* The widget's desired size.
   */
  GtkRequisition GSEAL (requisition);
  
  /* The widget's allocated size.
   */
  GtkAllocation GSEAL (allocation);
  
  /* The widget's window or its parent window if it does
   *  not have a window. (Which will be indicated by the
   *  GTK_NO_WINDOW flag being set).
   */
  GdkWindow *GSEAL (window);
  
  /* The widget's parent.
   */
  GtkWidget *GSEAL (parent);
} GtkWidget;

GtkWidgetClass

typedef struct {
  /* The object class structure needs to be the first
   *  element in the widget class structure in order for
   *  the class mechanism to work correctly. This allows a
   *  GtkWidgetClass pointer to be cast to a GtkObjectClass
   *  pointer.
   */
  GtkObjectClass parent_class;

  
  guint activate_signal;

  guint set_scroll_adjustments_signal;
} GtkWidgetClass;

activate_signal The signal to emit when a widget of this class is activated, gtk_widget_activate() handles the emission. Implementation of this signal is optional.

set_scroll_adjustment_signal This signal is emitted when a widget of this class is added to a scrolling aware parent, gtk_widget_set_scroll_adjustments() handles the emission. Implementation of this signal is optional.

enum GtkWidgetFlags

typedef enum
{
  GTK_TOPLEVEL         = 1 << 4,
  GTK_NO_WINDOW        = 1 << 5,
  GTK_REALIZED         = 1 << 6,
  GTK_MAPPED           = 1 << 7,
  GTK_VISIBLE          = 1 << 8,
  GTK_SENSITIVE        = 1 << 9,
  GTK_PARENT_SENSITIVE = 1 << 10,
  GTK_CAN_FOCUS        = 1 << 11,
  GTK_HAS_FOCUS        = 1 << 12,
  GTK_CAN_DEFAULT      = 1 << 13,
  GTK_HAS_DEFAULT      = 1 << 14,
  GTK_HAS_GRAB	       = 1 << 15,
  GTK_RC_STYLE	       = 1 << 16,
  GTK_COMPOSITE_CHILD  = 1 << 17,
  GTK_NO_REPARENT      = 1 << 18,
  GTK_APP_PAINTABLE    = 1 << 19,
  GTK_RECEIVES_DEFAULT = 1 << 20,
  GTK_DOUBLE_BUFFERED  = 1 << 21,
  GTK_NO_SHOW_ALL      = 1 << 22
} GtkWidgetFlags;

Tells about certain properties of the widget.

GTK_WIDGET_TYPE()

#define GTK_WIDGET_TYPE(wid)		  (GTK_OBJECT_TYPE (wid))

Gets the type of a widget.

GTK_WIDGET_STATE()

#define GTK_WIDGET_STATE(wid)		  (GTK_WIDGET (wid)->state)

GTK_WIDGET_SAVED_STATE()

#define GTK_WIDGET_SAVED_STATE(wid)	  (GTK_WIDGET (wid)->saved_state)

GTK_WIDGET_FLAGS()

#define GTK_WIDGET_FLAGS(wid)		  (GTK_OBJECT_FLAGS (wid))

GTK_WIDGET_TOPLEVEL()

#define GTK_WIDGET_TOPLEVEL(wid)	  ((GTK_WIDGET_FLAGS (wid) & GTK_TOPLEVEL) != 0)

Evaluates to TRUE if the widget is a toplevel widget.

GTK_WIDGET_NO_WINDOW()

#define GTK_WIDGET_NO_WINDOW(wid)	  ((GTK_WIDGET_FLAGS (wid) & GTK_NO_WINDOW) != 0)

Evaluates to TRUE if the widget doesn't have an own GdkWindow.

GTK_WIDGET_REALIZED()

#define GTK_WIDGET_REALIZED(wid)	  ((GTK_WIDGET_FLAGS (wid) & GTK_REALIZED) != 0)

Evaluates to TRUE if the widget is realized.

GTK_WIDGET_MAPPED()

#define GTK_WIDGET_MAPPED(wid)		  ((GTK_WIDGET_FLAGS (wid) & GTK_MAPPED) != 0)

Evaluates to TRUE if the widget is mapped.

GTK_WIDGET_VISIBLE()

#define GTK_WIDGET_VISIBLE(wid)		  ((GTK_WIDGET_FLAGS (wid) & GTK_VISIBLE) != 0)

Evaluates to TRUE if the widget is visible.

GTK_WIDGET_DRAWABLE()

#define GTK_WIDGET_DRAWABLE(wid)	  (GTK_WIDGET_VISIBLE (wid) && GTK_WIDGET_MAPPED (wid))

Evaluates to TRUE if the widget is mapped and visible.

GTK_WIDGET_SENSITIVE()

#define GTK_WIDGET_SENSITIVE(wid)	  ((GTK_WIDGET_FLAGS (wid) & GTK_SENSITIVE) != 0)

Evaluates to TRUE if the GTK_SENSITIVE flag has be set on the widget.

GTK_WIDGET_PARENT_SENSITIVE()

#define GTK_WIDGET_PARENT_SENSITIVE(wid)  ((GTK_WIDGET_FLAGS (wid) & GTK_PARENT_SENSITIVE) != 0)

Evaluates to TRUE if the GTK_PARENT_SENSITIVE flag has be set on the widget.

GTK_WIDGET_IS_SENSITIVE()

#define             GTK_WIDGET_IS_SENSITIVE(wid)

Evaluates to TRUE if the widget is effectively sensitive.

GTK_WIDGET_CAN_FOCUS()

#define GTK_WIDGET_CAN_FOCUS(wid)	  ((GTK_WIDGET_FLAGS (wid) & GTK_CAN_FOCUS) != 0)

Evaluates to TRUE if the widget is able to handle focus grabs.

GTK_WIDGET_HAS_FOCUS()

#define GTK_WIDGET_HAS_FOCUS(wid)	  ((GTK_WIDGET_FLAGS (wid) & GTK_HAS_FOCUS) != 0)

Evaluates to TRUE if the widget has grabbed the focus and no other widget has done so more recently.

GTK_WIDGET_CAN_DEFAULT()

#define GTK_WIDGET_CAN_DEFAULT(wid)	  ((GTK_WIDGET_FLAGS (wid) & GTK_CAN_DEFAULT) != 0)

Evaluates to TRUE if the widget is allowed to receive the default action via gtk_widget_grab_default().

GTK_WIDGET_RECEIVES_DEFAULT()

#define GTK_WIDGET_RECEIVES_DEFAULT(wid)  ((GTK_WIDGET_FLAGS (wid) & GTK_RECEIVES_DEFAULT) != 0)

Evaluates to TRUE if the widget when focused will receive the default action even if there is a different widget set as default.

GTK_WIDGET_HAS_DEFAULT()

#define GTK_WIDGET_HAS_DEFAULT(wid)	  ((GTK_WIDGET_FLAGS (wid) & GTK_HAS_DEFAULT) != 0)

Evaluates to TRUE if the widget currently is receiving the default action.

GTK_WIDGET_HAS_GRAB()

#define GTK_WIDGET_HAS_GRAB(wid)	  ((GTK_WIDGET_FLAGS (wid) & GTK_HAS_GRAB) != 0)

Evaluates to TRUE if the widget is in the grab_widgets stack, and will be the preferred one for receiving events other than ones of cosmetic value.

GTK_WIDGET_RC_STYLE()

#define GTK_WIDGET_RC_STYLE(wid)	  ((GTK_WIDGET_FLAGS (wid) & GTK_RC_STYLE) != 0)

Evaluates to TRUE if the widget's style has been looked up through the rc mechanism.

GTK_WIDGET_COMPOSITE_CHILD()

#define GTK_WIDGET_COMPOSITE_CHILD(wid)	  ((GTK_WIDGET_FLAGS (wid) & GTK_COMPOSITE_CHILD) != 0)

Evaluates to TRUE if the widget is a composite child of its parent.

GTK_WIDGET_APP_PAINTABLE()

#define GTK_WIDGET_APP_PAINTABLE(wid)	  ((GTK_WIDGET_FLAGS (wid) & GTK_APP_PAINTABLE) != 0)

Evaluates to TRUE if the GTK_APP_PAINTABLE flag has been set on the widget.

GTK_WIDGET_DOUBLE_BUFFERED()

#define GTK_WIDGET_DOUBLE_BUFFERED(wid)	  ((GTK_WIDGET_FLAGS (wid) & GTK_DOUBLE_BUFFERED) != 0)

Evaluates to TRUE if the GTK_DOUBLE_BUFFERED flag has been set on the widget.

GTK_WIDGET_SET_FLAGS()

#define GTK_WIDGET_SET_FLAGS(wid,flag)	  G_STMT_START{ (GTK_WIDGET_FLAGS (wid) |= (flag)); }G_STMT_END

Turns on certain widget flags.

GTK_WIDGET_UNSET_FLAGS()

#define GTK_WIDGET_UNSET_FLAGS(wid,flag)  G_STMT_START{ (GTK_WIDGET_FLAGS (wid) &= ~(flag)); }G_STMT_END

Turns off certain widget flags.

GtkCallback ()

void                (*GtkCallback)                      (GtkWidget *widget,
                                                         gpointer data);

The type of the callback functions used for e.g. iterating over the children of a container, see gtk_container_foreach().

GtkRequisition

typedef struct {
  gint width;
  gint height;
} GtkRequisition;

A GtkRequisition represents the desired size of a widget. See the section called “Size Requisition” for more information.

struct GtkAllocation

struct GtkAllocation {
  gint x;
  gint y;
  gint width;
  gint height;
};

A GtkAllocation of a widget represents region which has been allocated to the widget by its parent. It is a subregion of its parents allocation. See the section called “Size Allocation” for more information.

GtkSelectionData

typedef struct {
  GdkAtom       GSEAL (selection);
  GdkAtom       GSEAL (target);
  GdkAtom       GSEAL (type);
  gint          GSEAL (format);
  guchar       *GSEAL (data);
  gint          GSEAL (length);
  GdkDisplay   *GSEAL (display);
} GtkSelectionData;

GtkWidgetAuxInfo

typedef struct {
  gint x;
  gint y;
  gint width;
  gint height;
  guint x_set : 1;
  guint y_set : 1;
} GtkWidgetAuxInfo;

GtkWidgetShapeInfo

typedef struct {
  gint16     offset_x;
  gint16     offset_y;
  GdkBitmap *shape_mask;
} GtkWidgetShapeInfo;

enum GtkWidgetHelpType

typedef enum
{
  GTK_WIDGET_HELP_TOOLTIP,
  GTK_WIDGET_HELP_WHATS_THIS
} GtkWidgetHelpType;

gtk_widget_new ()

GtkWidget*          gtk_widget_new                      (GType type,
                                                         const gchar *first_property_name,
                                                         ...);

This is a convenience function for creating a widget and setting its properties in one go. For example you might write: gtk_widget_new (GTK_TYPE_LABEL, "label", "Hello World", "xalign", 0.0, NULL) to create a left-aligned label. Equivalent to g_object_new(), but returns a widget so you don't have to cast the object yourself.

gtk_widget_ref ()

GtkWidget*          gtk_widget_ref                      (GtkWidget *widget);

Adds a reference to a widget. This function is exactly the same as calling g_object_ref(), and exists mostly for historical reasons. It can still be convenient to avoid casting a widget to a GObject, it saves a small amount of typing.

gtk_widget_unref ()

void                gtk_widget_unref                    (GtkWidget *widget);

Inverse of gtk_widget_ref(). Equivalent to g_object_unref().

gtk_widget_destroy ()

void                gtk_widget_destroy                  (GtkWidget *widget);

Destroys a widget. Equivalent to gtk_object_destroy(), except that you don't have to cast the widget to GtkObject. When a widget is destroyed, it will break any references it holds to other objects. If the widget is inside a container, the widget will be removed from the container. If the widget is a toplevel (derived from GtkWindow), it will be removed from the list of toplevels, and the reference GTK+ holds to it will be removed. Removing a widget from its container or the list of toplevels results in the widget being finalized, unless you've added additional references to the widget with g_object_ref().

In most cases, only toplevel widgets (windows) require explicit destruction, because when you destroy a toplevel its children will be destroyed as well.

gtk_widget_destroyed ()

void                gtk_widget_destroyed                (GtkWidget *widget,
                                                         GtkWidget **widget_pointer);

This function sets *widget_pointer to NULL if widget_pointer != NULL. It's intended to be used as a callback connected to the "destroy" signal of a widget. You connect gtk_widget_destroyed() as a signal handler, and pass the address of your widget variable as user data. Then when the widget is destroyed, the variable will be set to NULL. Useful for example to avoid multiple copies of the same dialog.

gtk_widget_set ()

void                gtk_widget_set                      (GtkWidget *widget,
                                                         const gchar *first_property_name,
                                                         ...);

Precursor of g_object_set().

gtk_widget_unparent ()

void                gtk_widget_unparent                 (GtkWidget *widget);

This function is only for use in widget implementations. Should be called by implementations of the remove method on GtkContainer, to dissociate a child from the container.

gtk_widget_show ()

void                gtk_widget_show                     (GtkWidget *widget);

Flags a widget to be displayed. Any widget that isn't shown will not appear on the screen. If you want to show all the widgets in a container, it's easier to call gtk_widget_show_all() on the container, instead of individually showing the widgets.

Remember that you have to show the containers containing a widget, in addition to the widget itself, before it will appear onscreen.

When a toplevel container is shown, it is immediately realized and mapped; other shown widgets are realized and mapped when their toplevel container is realized and mapped.

gtk_widget_show_now ()

void                gtk_widget_show_now                 (GtkWidget *widget);

Shows a widget. If the widget is an unmapped toplevel widget (i.e. a GtkWindow that has not yet been shown), enter the main loop and wait for the window to actually be mapped. Be careful; because the main loop is running, anything can happen during this function.

gtk_widget_hide ()

void                gtk_widget_hide                     (GtkWidget *widget);

Reverses the effects of gtk_widget_show(), causing the widget to be hidden (invisible to the user).

gtk_widget_show_all ()

void                gtk_widget_show_all                 (GtkWidget *widget);

Recursively shows a widget, and any child widgets (if the widget is a container).

gtk_widget_hide_all ()

void                gtk_widget_hide_all                 (GtkWidget *widget);

Recursively hides a widget and any child widgets.

gtk_widget_map ()

void                gtk_widget_map                      (GtkWidget *widget);

This function is only for use in widget implementations. Causes a widget to be mapped if it isn't already.

gtk_widget_unmap ()

void                gtk_widget_unmap                    (GtkWidget *widget);

This function is only for use in widget implementations. Causes a widget to be unmapped if it's currently mapped.

gtk_widget_realize ()

void                gtk_widget_realize                  (GtkWidget *widget);

Creates the GDK (windowing system) resources associated with a widget. For example, widget->window will be created when a widget is realized. Normally realization happens implicitly; if you show a widget and all its parent containers, then the widget will be realized and mapped automatically.

Realizing a widget requires all the widget's parent widgets to be realized; calling gtk_widget_realize() realizes the widget's parents in addition to widget itself. If a widget is not yet inside a toplevel window when you realize it, bad things will happen.

This function is primarily used in widget implementations, and isn't very useful otherwise. Many times when you think you might need it, a better approach is to connect to a signal that will be called after the widget is realized automatically, such as GtkWidget::expose-event. Or simply g_signal_connect() to the GtkWidget::realize signal.

gtk_widget_unrealize ()

void                gtk_widget_unrealize                (GtkWidget *widget);

This function is only useful in widget implementations. Causes a widget to be unrealized (frees all GDK resources associated with the widget, such as widget->window).

gtk_widget_queue_draw ()

void                gtk_widget_queue_draw               (GtkWidget *widget);

Equivalent to calling gtk_widget_queue_draw_area() for the entire area of a widget.

gtk_widget_queue_resize ()

void                gtk_widget_queue_resize             (GtkWidget *widget);

This function is only for use in widget implementations. Flags a widget to have its size renegotiated; should be called when a widget for some reason has a new size request. For example, when you change the text in a GtkLabel, GtkLabel queues a resize to ensure there's enough space for the new text.

gtk_widget_queue_resize_no_redraw ()

void                gtk_widget_queue_resize_no_redraw   (GtkWidget *widget);

This function works like gtk_widget_queue_resize(), except that the widget is not invalidated.

Since 2.4

gtk_widget_draw ()

void                gtk_widget_draw                     (GtkWidget *widget,
                                                         const GdkRectangle *area);

In GTK+ 1.2, this function would immediately render the region area of a widget, by invoking the virtual draw method of a widget. In GTK+ 2.0, the draw method is gone, and instead gtk_widget_draw() simply invalidates the specified region of the widget, then updates the invalid region of the widget immediately. Usually you don't want to update the region immediately for performance reasons, so in general gtk_widget_queue_draw_area() is a better choice if you want to draw a region of a widget.

gtk_widget_size_request ()

void                gtk_widget_size_request             (GtkWidget *widget,
                                                         GtkRequisition *requisition);

This function is typically used when implementing a GtkContainer subclass. Obtains the preferred size of a widget. The container uses this information to arrange its child widgets and decide what size allocations to give them with gtk_widget_size_allocate().

You can also call this function from an application, with some caveats. Most notably, getting a size request requires the widget to be associated with a screen, because font information may be needed. Multihead-aware applications should keep this in mind.

Also remember that the size request is not necessarily the size a widget will actually be allocated.

See also gtk_widget_get_child_requisition().

gtk_widget_get_child_requisition ()

void                gtk_widget_get_child_requisition    (GtkWidget *widget,
                                                         GtkRequisition *requisition);

This function is only for use in widget implementations. Obtains widget->requisition, unless someone has forced a particular geometry on the widget (e.g. with gtk_widget_set_size_request()), in which case it returns that geometry instead of the widget's requisition.

This function differs from gtk_widget_size_request() in that it retrieves the last size request value from widget->requisition, while gtk_widget_size_request() actually calls the "size_request" method on widget to compute the size request and fill in widget->requisition, and only then returns widget->requisition.

Because this function does not call the "size_request" method, it can only be used when you know that widget->requisition is up-to-date, that is, gtk_widget_size_request() has been called since the last time a resize was queued. In general, only container implementations have this information; applications should use gtk_widget_size_request().

gtk_widget_size_allocate ()

void                gtk_widget_size_allocate            (GtkWidget *widget,
                                                         GtkAllocation *allocation);

This function is only used by GtkContainer subclasses, to assign a size and position to their child widgets.

gtk_widget_add_accelerator ()

void                gtk_widget_add_accelerator          (GtkWidget *widget,
                                                         const gchar *accel_signal,
                                                         GtkAccelGroup *accel_group,
                                                         guint accel_key,
                                                         GdkModifierType accel_mods,
                                                         GtkAccelFlags accel_flags);

Installs an accelerator for this widget in accel_group that causes accel_signal to be emitted if the accelerator is activated. The accel_group needs to be added to the widget's toplevel via gtk_window_add_accel_group(), and the signal must be of type G_RUN_ACTION. Accelerators added through this function are not user changeable during runtime. If you want to support accelerators that can be changed by the user, use gtk_accel_map_add_entry() and gtk_widget_set_accel_path() or gtk_menu_item_set_accel_path() instead.

gtk_widget_remove_accelerator ()

gboolean            gtk_widget_remove_accelerator       (GtkWidget *widget,
                                                         GtkAccelGroup *accel_group,
                                                         guint accel_key,
                                                         GdkModifierType accel_mods);

Removes an accelerator from widget, previously installed with gtk_widget_add_accelerator().

gtk_widget_set_accel_path ()

void                gtk_widget_set_accel_path           (GtkWidget *widget,
                                                         const gchar *accel_path,
                                                         GtkAccelGroup *accel_group);

Given an accelerator group, accel_group, and an accelerator path, accel_path, sets up an accelerator in accel_group so whenever the key binding that is defined for accel_path is pressed, widget will be activated. This removes any accelerators (for any accelerator group) installed by previous calls to gtk_widget_set_accel_path(). Associating accelerators with paths allows them to be modified by the user and the modifications to be saved for future use. (See gtk_accel_map_save().)

This function is a low level function that would most likely be used by a menu creation system like GtkUIManager. If you use GtkUIManager, setting up accelerator paths will be done automatically.

Even when you you aren't using GtkUIManager, if you only want to set up accelerators on menu items gtk_menu_item_set_accel_path() provides a somewhat more convenient interface.

Note that accel_path string will be stored in a GQuark. Therefore, if you pass a static string, you can save some memory by interning it first with g_intern_static_string().

gtk_widget_list_accel_closures ()

GList*              gtk_widget_list_accel_closures      (GtkWidget *widget);

Lists the closures used by widget for accelerator group connections with gtk_accel_group_connect_by_path() or gtk_accel_group_connect(). The closures can be used to monitor accelerator changes on widget, by connecting to the GtkAccelGroup::accel-changed signal of the GtkAccelGroup of a closure which can be found out with gtk_accel_group_from_accel_closure().

gtk_widget_can_activate_accel ()

gboolean            gtk_widget_can_activate_accel       (GtkWidget *widget,
                                                         guint signal_id);

Determines whether an accelerator that activates the signal identified by signal_id can currently be activated. This is done by emitting the "can-activate-accel" signal on widget; if the signal isn't overridden by a handler or in a derived widget, then the default check is that the widget must be sensitive, and the widget and all its ancestors mapped.

Since 2.4

gtk_widget_event ()

gboolean            gtk_widget_event                    (GtkWidget *widget,
                                                         GdkEvent *event);

Rarely-used function. This function is used to emit the event signals on a widget (those signals should never be emitted without using this function to do so). If you want to synthesize an event though, don't use this function; instead, use gtk_main_do_event() so the event will behave as if it were in the event queue. Don't synthesize expose events; instead, use gdk_window_invalidate_rect() to invalidate a region of the window.

gtk_widget_activate ()

gboolean            gtk_widget_activate                 (GtkWidget *widget);

For widgets that can be "activated" (buttons, menu items, etc.) this function activates them. Activation is what happens when you press Enter on a widget during key navigation. If widget isn't activatable, the function returns FALSE.

gtk_widget_reparent ()

void                gtk_widget_reparent                 (GtkWidget *widget,
                                                         GtkWidget *new_parent);

Moves a widget from one GtkContainer to another, handling reference count issues to avoid destroying the widget.

gtk_widget_intersect ()

gboolean            gtk_widget_intersect                (GtkWidget *widget,
                                                         const GdkRectangle *area,
                                                         GdkRectangle *intersection);

Computes the intersection of a widget's area and area, storing the intersection in intersection, and returns TRUE if there was an intersection. intersection may be NULL if you're only interested in whether there was an intersection.

gtk_widget_is_focus ()

gboolean            gtk_widget_is_focus                 (GtkWidget *widget);

Determines if the widget is the focus widget within its toplevel. (This does not mean that the HAS_FOCUS flag is necessarily set; HAS_FOCUS will only be set if the toplevel widget additionally has the global input focus.)

gtk_widget_grab_focus ()

void                gtk_widget_grab_focus               (GtkWidget *widget);

Causes widget to have the keyboard focus for the GtkWindow it's inside. widget must be a focusable widget, such as a GtkEntry; something like GtkFrame won't work.

More precisely, it must have the GTK_CAN_FOCUS flag set. Use gtk_widget_set_can_focus() to modify that flag.

gtk_widget_grab_default ()

void                gtk_widget_grab_default             (GtkWidget *widget);

Causes widget to become the default widget. widget must have the GTK_CAN_DEFAULT flag set; typically you have to set this flag yourself by calling gtk_widget_set_can_default (widget, TRUE). The default widget is activated when the user presses Enter in a window. Default widgets must be activatable, that is, gtk_widget_activate() should affect them.

gtk_widget_set_name ()

void                gtk_widget_set_name                 (GtkWidget *widget,
                                                         const gchar *name);

Widgets can be named, which allows you to refer to them from a gtkrc file. You can apply a style to widgets with a particular name in the gtkrc file. See the documentation for gtkrc files (on the same page as the docs for GtkRcStyle).

Note that widget names are separated by periods in paths (see gtk_widget_path()), so names with embedded periods may cause confusion.

gtk_widget_get_name ()

const gchar*        gtk_widget_get_name                 (GtkWidget *widget);

Retrieves the name of a widget. See gtk_widget_set_name() for the significance of widget names.

gtk_widget_set_state ()

void                gtk_widget_set_state                (GtkWidget *widget,
                                                         GtkStateType state);

This function is for use in widget implementations. Sets the state of a widget (insensitive, prelighted, etc.) Usually you should set the state using wrapper functions such as gtk_widget_set_sensitive().

gtk_widget_set_sensitive ()

void                gtk_widget_set_sensitive            (GtkWidget *widget,
                                                         gboolean sensitive);

Sets the sensitivity of a widget. A widget is sensitive if the user can interact with it. Insensitive widgets are "grayed out" and the user can't interact with them. Insensitive widgets are known as "inactive", "disabled", or "ghosted" in some other toolkits.

gtk_widget_set_parent ()

void                gtk_widget_set_parent               (GtkWidget *widget,
                                                         GtkWidget *parent);

This function is useful only when implementing subclasses of GtkContainer. Sets the container as the parent of widget, and takes care of some details such as updating the state and style of the child to reflect its new location. The opposite function is gtk_widget_unparent().

gtk_widget_set_parent_window ()

void                gtk_widget_set_parent_window        (GtkWidget *widget,
                                                         GdkWindow *parent_window);

Sets a non default parent window for widget.

gtk_widget_get_parent_window ()

GdkWindow *         gtk_widget_get_parent_window        (GtkWidget *widget);

Gets widget's parent window.

gtk_widget_set_uposition ()

void                gtk_widget_set_uposition            (GtkWidget *widget,
                                                         gint x,
                                                         gint y);

Sets the position of a widget. The funny "u" in the name comes from the "user position" hint specified by the X Window System, and exists for legacy reasons. This function doesn't work if a widget is inside a container; it's only really useful on GtkWindow.

Don't use this function to center dialogs over the main application window; most window managers will do the centering on your behalf if you call gtk_window_set_transient_for(), and it's really not possible to get the centering to work correctly in all cases from application code. But if you insist, use gtk_window_set_position() to set GTK_WIN_POS_CENTER_ON_PARENT, don't do the centering manually.

Note that although x and y can be individually unset, the position is not honoured unless both x and y are set.

gtk_widget_set_usize ()

void                gtk_widget_set_usize                (GtkWidget *widget,
                                                         gint width,
                                                         gint height);

Sets the minimum size of a widget; that is, the widget's size request will be width by height. You can use this function to force a widget to be either larger or smaller than it is. The strange "usize" name dates from the early days of GTK+, and derives from X Window System terminology. In many cases, gtk_window_set_default_size() is a better choice for toplevel windows than this function; setting the default size will still allow users to shrink the window. Setting the usize will force them to leave the window at least as large as the usize. When dealing with window sizes, gtk_window_set_geometry_hints() can be a useful function as well.

Note the inherent danger of setting any fixed size - themes, translations into other languages, different fonts, and user action can all change the appropriate size for a given widget. So, it's basically impossible to hardcode a size that will always be correct.

gtk_widget_set_events ()

void                gtk_widget_set_events               (GtkWidget *widget,
                                                         gint events);

Sets the event mask (see GdkEventMask) for a widget. The event mask determines which events a widget will receive. Keep in mind that different widgets have different default event masks, and by changing the event mask you may disrupt a widget's functionality, so be careful. This function must be called while a widget is unrealized. Consider gtk_widget_add_events() for widgets that are already realized, or if you want to preserve the existing event mask. This function can't be used with GTK_NO_WINDOW widgets; to get events on those widgets, place them inside a GtkEventBox and receive events on the event box.

gtk_widget_add_events ()

void                gtk_widget_add_events               (GtkWidget *widget,
                                                         gint events);

Adds the events in the bitfield events to the event mask for widget. See gtk_widget_set_events() for details.

gtk_widget_set_extension_events ()

void                gtk_widget_set_extension_events     (GtkWidget *widget,
                                                         GdkExtensionMode mode);

Sets the extension events mask to mode. See GdkExtensionMode and gdk_input_set_extension_events().

gtk_widget_get_extension_events ()

GdkExtensionMode    gtk_widget_get_extension_events     (GtkWidget *widget);

Retrieves the extension events the widget will receive; see gdk_input_set_extension_events().

gtk_widget_get_toplevel ()

GtkWidget*          gtk_widget_get_toplevel             (GtkWidget *widget);

This function returns the topmost widget in the container hierarchy widget is a part of. If widget has no parent widgets, it will be returned as the topmost widget. No reference will be added to the returned widget; it should not be unreferenced.

Note the difference in behavior vs. gtk_widget_get_ancestor(); gtk_widget_get_ancestor (widget, GTK_TYPE_WINDOW) would return NULL if widget wasn't inside a toplevel window, and if the window was inside a GtkWindow-derived widget which was in turn inside the toplevel GtkWindow. While the second case may seem unlikely, it actually happens when a GtkPlug is embedded inside a GtkSocket within the same application.

To reliably find the toplevel GtkWindow, use gtk_widget_get_toplevel() and check if the TOPLEVEL flags is set on the result.

1
2
3
4
5

GtkWidget *toplevel = gtk_widget_get_toplevel (widget);
if (gtk_widget_is_toplevel (toplevel))
  {
    /* Perform action on toplevel. */
  }

gtk_widget_get_ancestor ()

GtkWidget*          gtk_widget_get_ancestor             (GtkWidget *widget,
                                                         GType widget_type);

Gets the first ancestor of widget with type widget_type. For example, gtk_widget_get_ancestor (widget, GTK_TYPE_BOX) gets the first GtkBox that's an ancestor of widget. No reference will be added to the returned widget; it should not be unreferenced. See note about checking for a toplevel GtkWindow in the docs for gtk_widget_get_toplevel().

Note that unlike gtk_widget_is_ancestor(), gtk_widget_get_ancestor() considers widget to be an ancestor of itself.

gtk_widget_get_colormap ()

GdkColormap*        gtk_widget_get_colormap             (GtkWidget *widget);

Gets the colormap that will be used to render widget. No reference will be added to the returned colormap; it should not be unreferenced.

gtk_widget_set_colormap ()

void                gtk_widget_set_colormap             (GtkWidget *widget,
                                                         GdkColormap *colormap);

Sets the colormap for the widget to the given value. Widget must not have been previously realized. This probably should only be used from an init() function (i.e. from the constructor for the widget).

gtk_widget_get_visual ()

GdkVisual*          gtk_widget_get_visual               (GtkWidget *widget);

Gets the visual that will be used to render widget.

gtk_widget_get_events ()

gint                gtk_widget_get_events               (GtkWidget *widget);

Returns the event mask for the widget (a bitfield containing flags from the GdkEventMask enumeration). These are the events that the widget will receive.

gtk_widget_get_pointer ()

void                gtk_widget_get_pointer              (GtkWidget *widget,
                                                         gint *x,
                                                         gint *y);

Obtains the location of the mouse pointer in widget coordinates. Widget coordinates are a bit odd; for historical reasons, they are defined as widget->window coordinates for widgets that are not GTK_NO_WINDOW widgets, and are relative to widget->allocation.x, widget->allocation.y for widgets that are GTK_NO_WINDOW widgets.

gtk_widget_is_ancestor ()

gboolean            gtk_widget_is_ancestor              (GtkWidget *widget,
                                                         GtkWidget *ancestor);

Determines whether widget is somewhere inside ancestor, possibly with intermediate containers.

gtk_widget_translate_coordinates ()

gboolean            gtk_widget_translate_coordinates    (GtkWidget *src_widget,
                                                         GtkWidget *dest_widget,
                                                         gint src_x,
                                                         gint src_y,
                                                         gint *dest_x,
                                                         gint *dest_y);

Translate coordinates relative to src_widget's allocation to coordinates relative to dest_widget's allocations. In order to perform this operation, both widgets must be realized, and must share a common toplevel.

gtk_widget_hide_on_delete ()

gboolean            gtk_widget_hide_on_delete           (GtkWidget *widget);

Utility function; intended to be connected to the "delete-event" signal on a GtkWindow. The function calls gtk_widget_hide() on its argument, then returns TRUE. If connected to ::delete-event, the result is that clicking the close button for a window (on the window frame, top right corner usually) will hide but not destroy the window. By default, GTK+ destroys windows when ::delete-event is received.

gtk_widget_set_style ()

void                gtk_widget_set_style                (GtkWidget *widget,
                                                         GtkStyle *style);

Sets the GtkStyle for a widget (widget->style). You probably don't want to use this function; it interacts badly with themes, because themes work by replacing the GtkStyle. Instead, use gtk_widget_modify_style().

gtk_widget_set_rc_style()

#define gtk_widget_set_rc_style(widget)          (gtk_widget_set_style (widget, NULL))

Equivalent to gtk_widget_set_style (widget, NULL).

gtk_widget_ensure_style ()

void                gtk_widget_ensure_style             (GtkWidget *widget);

Ensures that widget has a style (widget->style). Not a very useful function; most of the time, if you want the style, the widget is realized, and realized widgets are guaranteed to have a style already.

gtk_widget_get_style ()

GtkStyle *          gtk_widget_get_style                (GtkWidget *widget);

Simply an accessor function that returns widget->style.

gtk_widget_restore_default_style()

#define gtk_widget_restore_default_style(widget) (gtk_widget_set_style (widget, NULL))

Equivalent to gtk_widget_set_style (widget, NULL).

gtk_widget_reset_rc_styles ()

void                gtk_widget_reset_rc_styles          (GtkWidget *widget);

Reset the styles of widget and all descendents, so when they are looked up again, they get the correct values for the currently loaded RC file settings.

This function is not useful for applications.

gtk_widget_push_colormap ()

void                gtk_widget_push_colormap            (GdkColormap *cmap);

Pushes cmap onto a global stack of colormaps; the topmost colormap on the stack will be used to create all widgets. Remove cmap with gtk_widget_pop_colormap(). There's little reason to use this function.

gtk_widget_pop_colormap ()

void                gtk_widget_pop_colormap             (void);

Removes a colormap pushed with gtk_widget_push_colormap().

gtk_widget_set_default_colormap ()

void                gtk_widget_set_default_colormap     (GdkColormap *colormap);

Sets the default colormap to use when creating widgets. gtk_widget_push_colormap() is a better function to use if you only want to affect a few widgets, rather than all widgets.

gtk_widget_get_default_style ()

GtkStyle*           gtk_widget_get_default_style        (void);

Returns the default style used by all widgets initially.

gtk_widget_get_default_colormap ()

GdkColormap*        gtk_widget_get_default_colormap     (void);

Obtains the default colormap used to create widgets.

gtk_widget_get_default_visual ()

GdkVisual*          gtk_widget_get_default_visual       (void);

Obtains the visual of the default colormap. Not really useful; used to be useful before gdk_colormap_get_visual() existed.

gtk_widget_set_direction ()

void                gtk_widget_set_direction            (GtkWidget *widget,
                                                         GtkTextDirection dir);

Sets the reading direction on a particular widget. This direction controls the primary direction for widgets containing text, and also the direction in which the children of a container are packed. The ability to set the direction is present in order so that correct localization into languages with right-to-left reading directions can be done. Generally, applications will let the default reading direction present, except for containers where the containers are arranged in an order that is explicitely visual rather than logical (such as buttons for text justification).

If the direction is set to GTK_TEXT_DIR_NONE, then the value set by gtk_widget_set_default_direction() will be used.

enum GtkTextDirection

typedef enum
{
  GTK_TEXT_DIR_NONE,
  GTK_TEXT_DIR_LTR,
  GTK_TEXT_DIR_RTL
} GtkTextDirection;

gtk_widget_get_direction ()

GtkTextDirection    gtk_widget_get_direction            (GtkWidget *widget);

Gets the reading direction for a particular widget. See gtk_widget_set_direction().

gtk_widget_set_default_direction ()

void                gtk_widget_set_default_direction    (GtkTextDirection dir);

Sets the default reading direction for widgets where the direction has not been explicitly set by gtk_widget_set_direction().

gtk_widget_get_default_direction ()

GtkTextDirection    gtk_widget_get_default_direction    (void);

Obtains the current default reading direction. See gtk_widget_set_default_direction().

gtk_widget_shape_combine_mask ()

void                gtk_widget_shape_combine_mask       (GtkWidget *widget,
                                                         GdkBitmap *shape_mask,
                                                         gint offset_x,
                                                         gint offset_y);

Sets a shape for this widget's GDK window. This allows for transparent windows etc., see gdk_window_shape_combine_mask() for more information.

gtk_widget_input_shape_combine_mask ()

void                gtk_widget_input_shape_combine_mask (GtkWidget *widget,
                                                         GdkBitmap *shape_mask,
                                                         gint offset_x,
                                                         gint offset_y);

Sets an input shape for this widget's GDK window. This allows for windows which react to mouse click in a nonrectangular region, see gdk_window_input_shape_combine_mask() for more information.

Since 2.10

gtk_widget_path ()

void                gtk_widget_path                     (GtkWidget *widget,
                                                         guint *path_length,
                                                         gchar **path,
                                                         gchar **path_reversed);

Obtains the full path to widget. The path is simply the name of a widget and all its parents in the container hierarchy, separated by periods. The name of a widget comes from gtk_widget_get_name(). Paths are used to apply styles to a widget in gtkrc configuration files. Widget names are the type of the widget by default (e.g. "GtkButton") or can be set to an application-specific value with gtk_widget_set_name(). By setting the name of a widget, you allow users or theme authors to apply styles to that specific widget in their gtkrc file. path_reversed_p fills in the path in reverse order, i.e. starting with widget's name instead of starting with the name of widget's outermost ancestor.

gtk_widget_class_path ()

void                gtk_widget_class_path               (GtkWidget *widget,
                                                         guint *path_length,
                                                         gchar **path,
                                                         gchar **path_reversed);

Same as gtk_widget_path(), but always uses the name of a widget's type, never uses a custom name set with gtk_widget_set_name().

gtk_widget_get_composite_name ()

gchar*              gtk_widget_get_composite_name       (GtkWidget *widget);

Obtains the composite name of a widget.

gtk_widget_modify_style ()

void                gtk_widget_modify_style             (GtkWidget *widget,
                                                         GtkRcStyle *style);

Modifies style values on the widget. Modifications made using this technique take precedence over style values set via an RC file, however, they will be overriden if a style is explicitely set on the widget using gtk_widget_set_style(). The GtkRcStyle structure is designed so each field can either be set or unset, so it is possible, using this function, to modify some style values and leave the others unchanged.

Note that modifications made with this function are not cumulative with previous calls to gtk_widget_modify_style() or with such functions as gtk_widget_modify_fg(). If you wish to retain previous values, you must first call gtk_widget_get_modifier_style(), make your modifications to the returned style, then call gtk_widget_modify_style() with that style. On the other hand, if you first call gtk_widget_modify_style(), subsequent calls to such functions gtk_widget_modify_fg() will have a cumulative effect with the initial modifications.

gtk_widget_get_modifier_style ()

GtkRcStyle *        gtk_widget_get_modifier_style       (GtkWidget *widget);

Returns the current modifier style for the widget. (As set by gtk_widget_modify_style().) If no style has previously set, a new GtkRcStyle will be created with all values unset, and set as the modifier style for the widget. If you make changes to this rc style, you must call gtk_widget_modify_style(), passing in the returned rc style, to make sure that your changes take effect.

Caution: passing the style back to gtk_widget_modify_style() will normally end up destroying it, because gtk_widget_modify_style() copies the passed-in style and sets the copy as the new modifier style, thus dropping any reference to the old modifier style. Add a reference to the modifier style if you want to keep it alive.

gtk_widget_modify_fg ()

void                gtk_widget_modify_fg                (GtkWidget *widget,
                                                         GtkStateType state,
                                                         const GdkColor *color);

Sets the foreground color for a widget in a particular state. All other style values are left untouched. See also gtk_widget_modify_style().

gtk_widget_modify_bg ()

void                gtk_widget_modify_bg                (GtkWidget *widget,
                                                         GtkStateType state,
                                                         const GdkColor *color);

Sets the background color for a widget in a particular state. All other style values are left untouched. See also gtk_widget_modify_style().

Note that "no window" widgets (which have the GTK_NO_WINDOW flag set) draw on their parent container's window and thus may not draw any background themselves. This is the case for e.g. GtkLabel. To modify the background of such widgets, you have to set the background color on their parent; if you want to set the background of a rectangular area around a label, try placing the label in a GtkEventBox widget and setting the background color on that.

gtk_widget_modify_text ()

void                gtk_widget_modify_text              (GtkWidget *widget,
                                                         GtkStateType state,
                                                         const GdkColor *color);

Sets the text color for a widget in a particular state. All other style values are left untouched. The text color is the foreground color used along with the base color (see gtk_widget_modify_base()) for widgets such as GtkEntry and GtkTextView. See also gtk_widget_modify_style().

gtk_widget_modify_base ()

void                gtk_widget_modify_base              (GtkWidget *widget,
                                                         GtkStateType state,
                                                         const GdkColor *color);

Sets the base color for a widget in a particular state. All other style values are left untouched. The base color is the background color used along with the text color (see gtk_widget_modify_text()) for widgets such as GtkEntry and GtkTextView. See also gtk_widget_modify_style().

Note that "no window" widgets (which have the GTK_NO_WINDOW flag set) draw on their parent container's window and thus may not draw any background themselves. This is the case for e.g. GtkLabel. To modify the background of such widgets, you have to set the base color on their parent; if you want to set the background of a rectangular area around a label, try placing the label in a GtkEventBox widget and setting the base color on that.

gtk_widget_modify_font ()

void                gtk_widget_modify_font              (GtkWidget *widget,
                                                         PangoFontDescription *font_desc);

Sets the font to use for a widget. All other style values are left untouched. See also gtk_widget_modify_style().

gtk_widget_modify_cursor ()

void                gtk_widget_modify_cursor            (GtkWidget *widget,
                                                         const GdkColor *primary,
                                                         const GdkColor *secondary);

Sets the cursor color to use in a widget, overriding the "cursor-color" and "secondary-cursor-color" style properties. All other style values are left untouched. See also gtk_widget_modify_style().

Since 2.12

gtk_widget_create_pango_context ()

PangoContext *      gtk_widget_create_pango_context     (GtkWidget *widget);

Creates a new PangoContext with the appropriate font map, font description, and base direction for drawing text for this widget. See also gtk_widget_get_pango_context().

gtk_widget_get_pango_context ()

PangoContext *      gtk_widget_get_pango_context        (GtkWidget *widget);

Gets a PangoContext with the appropriate font map, font description, and base direction for this widget. Unlike the context returned by gtk_widget_create_pango_context(), this context is owned by the widget (it can be used until the screen for the widget changes or the widget is removed from its toplevel), and will be updated to match any changes to the widget's attributes.

If you create and keep a PangoLayout using this context, you must deal with changes to the context by calling pango_layout_context_changed() on the layout in response to the "style-set" and "direction-changed" signals for the widget.

gtk_widget_create_pango_layout ()

PangoLayout *       gtk_widget_create_pango_layout      (GtkWidget *widget,
                                                         const gchar *text);

Creates a new PangoLayout with the appropriate font map, font description, and base direction for drawing text for this widget.

If you keep a PangoLayout created in this way around, in order to notify the layout of changes to the base direction or font of this widget, you must call pango_layout_context_changed() in response to the "style-set" and "direction-changed" signals for the widget.

gtk_widget_render_icon ()

GdkPixbuf *         gtk_widget_render_icon              (GtkWidget *widget,
                                                         const gchar *stock_id,
                                                         GtkIconSize size,
                                                         const gchar *detail);

A convenience function that uses the theme engine and RC file settings for widget to look up stock_id and render it to a pixbuf. stock_id should be a stock icon ID such as GTK_STOCK_OPEN or GTK_STOCK_OK. size should be a size such as GTK_ICON_SIZE_MENU. detail should be a string that identifies the widget or code doing the rendering, so that theme engines can special-case rendering for that widget or code.

The pixels in the returned GdkPixbuf are shared with the rest of the application and should not be modified. The pixbuf should be freed after use with g_object_unref().

gtk_widget_pop_composite_child ()

void                gtk_widget_pop_composite_child      (void);

Cancels the effect of a previous call to gtk_widget_push_composite_child().

gtk_widget_push_composite_child ()

void                gtk_widget_push_composite_child     (void);

Makes all newly-created widgets as composite children until the corresponding gtk_widget_pop_composite_child() call.

A composite child is a child that's an implementation detail of the container it's inside and should not be visible to people using the container. Composite children aren't treated differently by GTK (but see gtk_container_foreach() vs. gtk_container_forall()), but e.g. GUI builders might want to treat them in a different way.

Here is a simple example:

1
2
3
4
5
6
7

gtk_widget_push_composite_child ();
scrolled_window->hscrollbar = gtk_hscrollbar_new (hadjustment);
gtk_widget_set_composite_name (scrolled_window->hscrollbar, "hscrollbar");
gtk_widget_pop_composite_child ();
gtk_widget_set_parent (scrolled_window->hscrollbar, 
                       GTK_WIDGET (scrolled_window));
g_object_ref (scrolled_window->hscrollbar);

gtk_widget_queue_clear ()

void                gtk_widget_queue_clear              (GtkWidget *widget);

This function does the same as gtk_widget_queue_draw().

gtk_widget_queue_clear_area ()

void                gtk_widget_queue_clear_area         (GtkWidget *widget,
                                                         gint x,
                                                         gint y,
                                                         gint width,
                                                         gint height);

This function is no longer different from gtk_widget_queue_draw_area(), though it once was. Now it just calls gtk_widget_queue_draw_area(). Originally gtk_widget_queue_clear_area() would force a redraw of the background for GTK_NO_WINDOW widgets, and gtk_widget_queue_draw_area() would not. Now both functions ensure the background will be redrawn.

gtk_widget_queue_draw_area ()

void                gtk_widget_queue_draw_area          (GtkWidget *widget,
                                                         gint x,
                                                         gint y,
                                                         gint width,
                                                         gint height);

Invalidates the rectangular area of widget defined by x, y, width and height by calling gdk_window_invalidate_rect() on the widget's window and all its child windows. Once the main loop becomes idle (after the current batch of events has been processed, roughly), the window will receive expose events for the union of all regions that have been invalidated.

Normally you would only use this function in widget implementations. You might also use it, or gdk_window_invalidate_rect() directly, to schedule a redraw of a GtkDrawingArea or some portion thereof.

Frequently you can just call gdk_window_invalidate_rect() or gdk_window_invalidate_region() instead of this function. Those functions will invalidate only a single window, instead of the widget and all its children.

The advantage of adding to the invalidated region compared to simply drawing immediately is efficiency; using an invalid region ensures that you only have to redraw one time.

gtk_widget_reset_shapes ()

void                gtk_widget_reset_shapes             (GtkWidget *widget);

Recursively resets the shape on this widget and its descendants.

gtk_widget_set_app_paintable ()

void                gtk_widget_set_app_paintable        (GtkWidget *widget,
                                                         gboolean app_paintable);

Sets whether the application intends to draw on the widget in an "expose-event" handler.

This is a hint to the widget and does not affect the behavior of the GTK+ core; many widgets ignore this flag entirely. For widgets that do pay attention to the flag, such as GtkEventBox and GtkWindow, the effect is to suppress default themed drawing of the widget's background. (Children of the widget will still be drawn.) The application is then entirely responsible for drawing the widget background.

Note that the background is still drawn when the widget is mapped. If this is not suitable (e.g. because you want to make a transparent window using an RGBA visual), you can work around this by doing:

1
2
3

gtk_widget_realize (window);
gdk_window_set_back_pixmap (window->window, NULL, FALSE);
gtk_widget_show (window);

gtk_widget_set_double_buffered ()

void                gtk_widget_set_double_buffered      (GtkWidget *widget,
                                                         gboolean double_buffered);

Widgets are double buffered by default; you can use this function to turn off the buffering. "Double buffered" simply means that gdk_window_begin_paint_region() and gdk_window_end_paint() are called automatically around expose events sent to the widget. gdk_window_begin_paint() diverts all drawing to a widget's window to an offscreen buffer, and gdk_window_end_paint() draws the buffer to the screen. The result is that users see the window update in one smooth step, and don't see individual graphics primitives being rendered.

In very simple terms, double buffered widgets don't flicker, so you would only use this function to turn off double buffering if you had special needs and really knew what you were doing.

Note: if you turn off double-buffering, you have to handle expose events, since even the clearing to the background color or pixmap will not happen automatically (as it is done in gdk_window_begin_paint()).

gtk_widget_set_redraw_on_allocate ()

void                gtk_widget_set_redraw_on_allocate   (GtkWidget *widget,
                                                         gboolean redraw_on_allocate);

Sets whether the entire widget is queued for drawing when its size allocation changes. By default, this setting is TRUE and the entire widget is redrawn on every size change. If your widget leaves the upper left unchanged when made bigger, turning this setting off will improve performance.

Note that for NO_WINDOW widgets setting this flag to FALSE turns off all allocation on resizing: the widget will not even redraw if its position changes; this is to allow containers that don't draw anything to avoid excess invalidations. If you set this flag on a NO_WINDOW widget that does draw on widget->window, you are responsible for invalidating both the old and new allocation of the widget when the widget is moved and responsible for invalidating regions newly when the widget increases size.

gtk_widget_set_composite_name ()

void                gtk_widget_set_composite_name       (GtkWidget *widget,
                                                         const gchar *name);