[REG] Cocoa: Enter event not delivered after showing and hiding context menu when mouse isn't over the menu

This doesn't happen always, but very often (it depends where the mouse cursor is).

Steps to reproduce:

• right click on text editor in QtCreator to open the context menu - the mouse cursor shape changes,
• left click to close the context menu (don't move the mouse),
• the mouse cursor shape doesn't change - missing enter event.

When the menu will popup to the top the mouse cursor shape isn't changed. It looks like Cocoa sends enter/leave events when the popup menu is opened to non-grabbed windows, so it causes problems with bad cursor shape (the same problem on Wayland).

This worked properly in Qt 5.4.2.

The test app from QTBUG-49222 can be used for testing this bug.