Fullscreen mode splits screen over monitor boundaries on dual-monitor system

I originally reported this for the Android SDK emulator, which is built on QEMU: http://code.google.com/p/android/issues/detail?id=14336

Can confirm that this bug is present in stock QEMU shipped with Ubuntu 10.10:
QEMU PC emulator version 0.12.5 (qemu-kvm-0.12.5), Copyright (c) 2003-2008 Fabrice Bellard

Steps to reproduce:
- get a Linux machine with multiple-monitor setup (tested using NVidia proprietary driver on Ubuntu 10.10 x86_64, with two monitors side-by-side in 'TwinView' configuration)
- launch qemu
- hit ctrl+alt+f to go into fullscreen mode

Expected behavior:
- emulator should take over one screen (either the first screen, largest screen, or screen the emulator is presently on)
- emulator's display should center or scale to fit within available area of the taken-over screen

Actual behavior:
- emulator takes over both screens
- emulator's display is split over the boundary between the two screens