[1.5] QEMU monitor gets overlapped by GTK menu bar

The QEMU minitor gets partially hidden by the menu bar which was introduced in QEMU version 1.5.0.

Steps to reproduce:

 1. Run `qemu-system-x86_64`
 2. Press Ctrl + Alt + 2 (or use the menu bar)
 3. Observe that the monitor output is partially shown, without the "compat_monitor0 console" and "QEMU 1.5.0 monitor - type 'help' for more information" lines.

Attached is a screenshot of `qemu-system-x86_64` and `qemu-system-x86_64 -display sdl`.

Version: 1.5.0
Distribution: Arch Linux 64-bit