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GtkEventBoxGtkEventBox — A widget used to catch events for widgets which do not have their own window |
Object Hierarchy
GObject ╰── GInitiallyUnowned ╰── GtkObject ╰── GtkWidget ╰── GtkContainer ╰── GtkBin ╰── GtkEventBox
Description
The GtkEventBox widget is a subclass of GtkBin which also has its own window. It is useful since it allows you to catch events for widgets which do not have their own window.
Functions
gtk_event_box_set_above_child ()
void gtk_event_box_set_above_child (GtkEventBox *event_box,gboolean above_child);
Set whether the event box window is positioned above the windows of its child, as opposed to below it. If the window is above, all events inside the event box will go to the event box. If the window is below, events in windows of child widgets will first got to that widget, and then to its parents.
The default is to keep the window below the child.
Since 2.4
gtk_event_box_get_above_child ()
gboolean
gtk_event_box_get_above_child (GtkEventBox *event_box);
Returns whether the event box window is above or below the
windows of its child. See gtk_event_box_set_above_child() for
details.
Since 2.4
gtk_event_box_set_visible_window ()
void gtk_event_box_set_visible_window (GtkEventBox *event_box,gboolean visible_window);
Set whether the event box uses a visible or invisible child window. The default is to use visible windows.
In an invisible window event box, the window that the
event box creates is a GDK_INPUT_ONLY window, which
means that it is invisible and only serves to receive
events.
A visible window event box creates a visible (GDK_INPUT_OUTPUT)
window that acts as the parent window for all the widgets
contained in the event box.
You should generally make your event box invisible if you just want to trap events. Creating a visible window may cause artifacts that are visible to the user, especially if the user is using a theme with gradients or pixmaps.
The main reason to create a non input-only event box is if you want to set the background to a different color or draw on it.
There is one unexpected issue for an invisible event box that has its
window below the child. (See gtk_event_box_set_above_child().)
Since the input-only window is not an ancestor window of any windows
that descendent widgets of the event box create, events on these
windows aren't propagated up by the windowing system, but only by GTK+.
The practical effect of this is if an event isn't in the event
mask for the descendant window (see gtk_widget_add_events()),
it won't be received by the event box.
This problem doesn't occur for visible event boxes, because in that case, the event box window is actually the ancestor of the descendant windows, not just at the same place on the screen.
Since 2.4
gtk_event_box_get_visible_window ()
gboolean
gtk_event_box_get_visible_window (GtkEventBox *event_box);
Returns whether the event box has a visible window.
See gtk_event_box_set_visible_window() for details.
Since 2.4
Types and Values
struct GtkEventBox
struct GtkEventBox;
The GtkEventBox struct contains private data only, and should be accessed using the functions below.
Property Details
The “above-child” property
“above-child” gboolean
Whether the event-trapping window of the eventbox is above the window of the child widget as opposed to below it.
Flags: Read / Write
Default value: FALSE
The “visible-window” property
“visible-window” gboolean
Whether the event box is visible, as opposed to invisible and only used to trap events.
Flags: Read / Write
Default value: TRUE