10.6.1 Normal Entry/Exit Events

EnterNotify and LeaveNotify events are generated when the pointer moves from one window to another window. Normal events are identified by XEnterWindowEvent or XLeaveWindowEvent structures whose mode member is set to NotifyNormal.

When the pointer moves from window A to window B and A is an inferior of B, the X server does the following:
- It generates a LeaveNotify event on window A, with the detail member of the XLeaveWindowEvent structure set to NotifyAncestor.
- It generates a LeaveNotify event on each window between window A and window B, exclusive, with the detail member of each XLeaveWindowEvent structure set to NotifyVirtual.
- It generates an EnterNotify event on window B, with the detail member of the XEnterWindowEvent structure set to NotifyInferior.
When the pointer moves from window A to window B and B is an inferior of A, the X server does the following:
- It generates a LeaveNotify event on window A, with the detail member of the XLeaveWindowEvent structure set to NotifyInferior.
- It generates an EnterNotify event on each window between window A and window B, exclusive, with the detail member of each XEnterWindowEvent structure set to NotifyVirtual.
- It generates an EnterNotify event on window B, with the detail member of the XEnterWindowEvent structure set to NotifyAncestor.
When the pointer moves from window A to window B and window C is their least common ancestor, the X server does the following:
- It generates a LeaveNotify event on window A, with the detail member of the XLeaveWindowEvent structure set to NotifyNonlinear.
- It generates a LeaveNotify event on each window between window A and window C, exclusive, with the detail member of each XLeaveWindowEvent structure set to NotifyNonlinearVirtual.
- It generates an EnterNotify event on each window between window C and window B, exclusive, with the detail member of each XEnterWindowEvent structure set to NotifyNonlinearVirtual.
- It generates an EnterNotify event on window B, with the detail member of the XEnterWindowEvent structure set to NotifyNonlinear.
When the pointer moves from window A to window B on different screens, the X server does the following:
- It generates a LeaveNotify event on window A, with the detail member of the XLeaveWindowEvent structure set to NotifyNonlinear.
- If window A is not a root window, it generates a LeaveNotify event on each window above window A up to and including its root, with the detail member of each XLeaveWindowEvent structure set to NotifyNonlinearVirtual.
- If window B is not a root window, it generates an EnterNotify event on each window from window B's root down to but not including window B, with the detail member of each XEnterWindowEvent structure set to NotifyNonlinearVirtual.
- It generates an EnterNotify event on window B, with the detail member of the XEnterWindowEvent structure set to NotifyNonlinear.

Next: Grab and Ungrab Entry/Exit Events

Christophe Tronche, ch@tronche.com