QEMU 6.2.0 fullscreen problem
Description of problem:
After running the command above, clicking on "Try Ubuntu" and adjusting the guest display resolution in GNOME to the native resolution, pressing ctrl+alt+f yields a "fullscreen" that only covers the QEMU window but not the entire host screen. This is not the case when switching to fullscreen while the boot screen is active or running `qemu-system-x86_64 -display gtk,full-screen=on`. 

The problem also occurs when replacing `-device qxl-vga` by `-device VGA,vgamem_mb=64`. The problem however does not occur when using `-device virtio-vga` instead of `-device qxl-vga` or `-display sdl` instead of `-display gtk`.
Steps to reproduce:
1. Run the command above
2. Click "Try Ubuntu"
3. Set guest resolution to native resolution (1920x1200 in my case)
4. Move the window a bit off the corners to observe the effect
5. Press ctrl+alt+f
Additional information:
The bug has also been [reported here](https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/2000739).