Description of problem:

I have it set up so double clicking on the title bar of a window
maximizes vertically.

However if I take one of these windows and move it left or right
(especially right for some reason), then the window is sometimes
maximized, so it fills the whole screen.  Clicking the maximize
button in the menu bar restores it to the original size.

Version-Release number of selected component (if applicable):

gnome-shell-2.91.91-2.fc15.x86_64

How reproducible:

Very often.

Steps to Reproduce:
1. Make a Windows which occupies all vertical space.
2. Move it by the title bar to the right.
3.
  
Actual results:

Windows suddenly fully maximize themselves for no apparent
reason.

Expected results:

Should just move, not maximize.

Additional info: