I sometimes use gvim 7.3 @ win7 (64 bit). When I move the gvim window by means 
of the <windows-key + left/right> key combination to the left or right half of 
the screen, it seems gvim doesn't properly notice this change. When I invoke 
any command with :vert prepended (e.g. :vert split), gvim moves the gvim window 
back to the previous position on the screen.

Steps:
1. Open gvim -> gvim window opens at position #1
2. Press <windows-left> -> gvim window is moved to the left (position #2)
3. Type :vert split

Result: The gvim window is back at position #1.

This problem seems to affect only the win gui. At least with gnome/gtk 
everything seems ok.

The problem also affects :tab-related commands. It was verified by a user. See 
https://groups.google.com/d/topic/vim_dev/MiKswL7hN6E/discussion