Binary package hint: light-themes
Problem occurs with: compiz 1:0.9.4+bzr20110415-0ubuntu2, light-themes 0.1.8.13, Ubuntu Natty
Does not occur with: Windows 7, Mac OS X
1. Open a highly-nested submenu, for example in Firefox "View" > "Character Encoding" > "More Encodings".
Observe that:
* The top-level menu has a shadow, showing that it is raised some non-zero distance from the desktop. Let's call this distance x.
* The first submenu overlaps the top-level menu by 2 pixels, showing that it is raised some non-zero distance from the top-level menu. Let's call this distance y.
* The second submenu similarly overlaps the first submenu by 2 pixels, showing that it is raised still further.
What you see: Somehow, the shadow the second submenu casts on the desktop is exactly the same as the shadow the top-level menu casts on the desktop. y > 0 but x + y + y = x, which is impossible.
What you should see: either
* submenus should have progressively deeper shadows, to show that they're raised higher and higher; or
* submenus should not overlap their parents.
Following the same principle as bug 659816, I suggest that Ubuntu follow Windows and Mac OS X in showing all levels of submenu as being at exactly the same height. This can be fixed by moving them 2 pixels to the right, so that they don't overlap their parents at all.
It looks like a regression from maverick: the sub-menus don't look like they are indented 2px on the left, so the shadows look normal.