10.6.2 Grab and Ungrab Entry/Exit Events

Pseudo-motion mode EnterNotify and LeaveNotify events are generated when a pointer grab activates or deactivates. Events in which the pointer grab activates are identified by XEnterWindowEvent or XLeaveWindowEvent structures whose mode member is set to NotifyGrab. Events in which the pointer grab deactivates are identified by XEnterWindowEvent or XLeaveWindowEvent structures whose mode member is set to NotifyUngrab (see XGrabPointer()).

• When a pointer grab activates after any initial warp into a confine_to window and before generating any actual ButtonPress event that activates the grab, G is the grab_window for the grab, and P is the window the pointer is in, the X server does the following:

  • It generates EnterNotify and LeaveNotify events (see "Normal Entry/Exit Events") with the mode members of the XEnterWindowEvent and XLeaveWindowEvent structures set to NotifyGrab. These events are generated as if the pointer were to suddenly warp from its current position in P to some position in G. However, the pointer does not warp, and the X server uses the pointer position as both the initial and final positions for the events.

• When a pointer grab deactivates after generating any actual ButtonRelease event that deactivates the grab, G is the grab_window for the grab, and P is the window the pointer is in, the X server does the following:

  • It generates EnterNotify and LeaveNotify events (see "Normal Entry/Exit Events") with the mode members of the XEnterWindowEvent and XLeaveWindowEvent structures set to NotifyUngrab. These events are generated as if the pointer were to suddenly warp from some position in G to its current position in P. However, the pointer does not warp, and the X server uses the current pointer position as both the initial and final positions for the events.

Next: Input Focus Events

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Christophe Tronche, [email protected]