Comment 3 for bug 1138489

Although this bug happens often with grid plugin, it's not the root cause of this issue (there was a bug in grid that has kept this problem hidden in the past). This bug can be reproduced with only core loaded by maximizing and restoring terminal window using key bindings.

When the window is unmaximized, gnome-terminal decides to recalculate its size (it reacts to focus in/out events, and when a keybinding or restore button is pressed, compiz steals the focus). For some reason it's using the maximized window geometry as a base of the process.

Also check out bug 1102024 (it's practically the same bug as this one but with different way to trigger it).