
When you open or close a PopupSubMenu the arrow icon rotates, but the code previously assumed that the starting angle was a multiple of 90. If you click the submenu fast enough the rotation could overlap with the previous rotation and you'd get something that wasn't a multiple of 90. Now we ensure that the ending arrowRotation angle is always a multiple of 90 regardless of what the starting angle is. https://bugzilla.gnome.org/show_bug.cgi?id=728927