Description:

While investigating issues with tooltips not disappearing in X11 apps running under Xwayland, I noticed that in some cases, the LeaveNotify event is not delivered to the X11 window when the pointer crosses from an X11 window to a Wayland native window.

Steps to reproduce:

1. Run xev and weston-terminal and place them so that the xev window is beneath the weston-terminal (Wayland native window) as follow :


              +----------------------------------+
              |                                  |
              | > weston-terminal                |
              |                                  |
              |                                  |
  +-----------|                                  |
  |           |                                  |
  |     xev   |                                  |
  |           |                                  |
  |           +----------------------------------+
  +--------------+

2. Move the mouse pointer from the xev to the weston-window and observe the events reported

Actual results:

MotionNotify events are reported until the pointer enters the native Wayland window but no LeaveNotify event is reported, even though the pointer has left the xev window to enter the Wayland native window.

Expected results:

As soon as the pointer actually leaves the X11 window, we should receive a LeaveNotify event.

Additional data:

If we move the pointer back to the xev window, we get a LeaveNotify followed immediately by an EnterNotify, as if the LeaveNotify was pending.