begin/end_modal doesn't trigger enter or leave events for shell actors
Starting or ending a modal grab should make sure the currently hovered actor receives a leave event or an enter event. This is not happening right now (only tested in X11-session).
This can easily be reproduced this by opening looking glass, hovering the pointer over a panel button, then opening the entry-menu using the menu-key (taking a modal grab), moving the pointer away from the button and closing the entry-menu again (releasing the grab). The panel button will remain highlighted because it didn't receive a leave-event. The same thing applies to the enter event, just enter the button while the menu is open to reproduce it.