The final size of a widget within its parent. For example, a widget may request a minimum size of 20×20 pixels, but its parent may decide to allocate 50×20 pixels for it instead.

See Also requisition .

A container that can hold at most one child widget. The base class for bins is GtkBin.

See Also container .

A container's child is a widget contained inside it.

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See Also model column, view column.

A widget that contains other widgets; in that case, the container is the parent of the child widgets. Some containers don't draw anything on their own, but rather just organize their children's geometry; for example, GtkVBox lays out its children vertically without painting anything on its own. Other containers include decorative elements; for example, GtkFrame contains the frame's child and a label in addition to the shaded frame it draws. The base class for containers is GtkContainer.

See Also widget geometry .

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A widget's position and size. Within its parent, this is called the widget's allocation.

This is the step in a widget's life cycle where it actually shows the GdkWindows it created when it was realized. When a widget is mapped, it must turn on its GTK_MAPPED flag.

Note that due to the asynchronous nature of the X window system, a widget's window may not appear on the screen immediatly after one calls gdk_window_show(): you must wait for the corresponding map event to be received. You can do this with the GtkWidget::map-event signal.

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A widget that does not have a GdkWindow of its own on which to draw its contents, but rather shares its parent's. Such a widget has the GTK_NO_WINDOW flag set, and can be tested with the GTK_WIDGET_NO_WINDOW() macro.

A widget's parent is the container inside which it resides.

This is the step in a widget's life cycle where it creates its own GdkWindow, or otherwise associates itself with its parent's GdkWindow. If the widget has its own window, then it must also attach a style to it. A widget becomes unrealized by destroying its associated GdkWindow. When a widget is realized, it must turn on its GTK_REALIZED flag.

Widgets that don't own the GdkWindow on which they draw are called no-window widgets. This can be tested with the GTK_WIDGET_NO_WINDOW() macro. Normally, these widgets draw on their parent's GdkWindow.

Note that when a widget creates a window in its ::realize() handler, it does not actually show the window. That is, the window's structure is just created in memory. The widget actually shows the window when it gets mapped.

The size requisition of a widget is the minimum amount of space it requests from its parent. Once the parent computes the widget's final size, it gives it its size allocation.

See Also allocation .

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A widget that does not require a parent container. The only toplevel widget in GTK+ is GtkWindow.

See Also container .

See mapping.

See realization.

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A control in a graphical user interface. Widgets can draw themselves and process events from the mouse and keyboard. Widget types include buttons, menus, text entry lines, and lists. Widgets can be arranged into containers, and these take care of assigning the geometry of the widgets: every widget thus has a parent except those widgets which are toplevels. The base class for widgets is GtkWidget.

See Also container .