gdkPointerGrab: gdkPointerGrab

Description

Grabs the pointer (usually a mouse) so that all events are passed to this application until the pointer is ungrabbed with gdkPointerUngrab, or the grab window becomes unviewable. This overrides any previous pointer grab by this client.

Usage

gdkPointerGrab(window, owner.events = FALSE, event.mask = 0,  confine.to = NULL, cursor = NULL, time = "GDK_CURRENT_TIME")

Arguments

window

the GdkWindow which will own the grab (the grab window).

owner.events

if FALSE then all pointer events are reported with respect to window and are only reported if selected by event.mask. If TRUE then pointer events for this application are reported as normal, but pointer events outside this application are reported with respect to window and only if selected by event.mask. In either mode, unreported events are discarded.

event.mask

specifies the event mask, which is used in accordance with owner.events. Note that only pointer events (i.e. button and motion events) may be selected.

confine.to

If non-NULL, the pointer will be confined to this window during the grab. If the pointer is outside confine.to, it will automatically be moved to the closest edge of confine.to and enter and leave events will be generated as necessary.

cursor

the cursor to display while the grab is active. If this is NULL then the normal cursors are used for window and its descendants, and the cursor for window is used for all other windows.

time

the timestamp of the event which led to this pointer grab. This usually comes from a GdkEventButton struct, though GDK_CURRENT_TIME can be used if the time isn't known.

Value

GdkGrabStatus] GDK_GRAB_SUCCESS if the grab was successful.

Details

Pointer grabs are used for operations which need complete control over mouse events, even if the mouse leaves the application. For example in GTK+ it is used for Drag and Drop, for dragging the handle in the GtkHPaned and GtkVPaned widgets, and for resizing columns in GtkCList widgets. Note that if the event mask of an X window has selected both button press and button release events, then a button press event will cause an automatic pointer grab until the button is released. X does this automatically since most applications expect to receive button press and release events in pairs. It is equivalent to a pointer grab on the window with owner.events set to TRUE. If you set up anything at the time you take the grab that needs to be cleaned up when the grab ends, you should handle the GdkEventGrabBroken events that are emitted when the grab ends unvoluntarily.