A new feature was added recently that adds an invisible border around the windows to grab for resizing (although i thought the new resize grip solved any big issues).
This annoys me because it destroys the usefulness of the grid plugin of compiz.. i'm not sure if the border is part of compiz or gnome, but i'd like to know how to disable it.
i couldn't find any options in ccsm or the window settings in gnome.
See the screenshot to see how much waste is caused. These windows should match up instead of having blank space surrounding all of them.
It's part of the theme.
Look into
/usr/share/themes/Ambiance/metacity-1/metacity-theme-1.xml
and change thepadding
properties to zero (or remove them), e.g:--- Update ---
There's now also a bug report to follow. The bug has been fixed, if you still see this, I'd report a new bug (unless it's happening with windows that can only be resized in fixed sized steps like gnome-terminal).
Simpler solution: run
gtk-window-decorator --replace &
in a terminal. Only unity-window-decorator supports this theme option but gtk-window-decorator supports the rest of the metacity theme.