When you open a menu or popover, moving your mouse to a neighboring
root menu button will switch to that one. For example when you open the
"File" menu and move to the right to have "Edit" open automatically.
This currently causes problems with some neighboring menus. This PR
adds a safety padding to the open item. This generally means that once
you open a menu, you will need to move your mouse into the neighbor's
content, not just hit the edge.
Pull Request: https://projects.blender.org/blender/blender/pulls/135692
166d45b80f