Due to having a laptop, I often switch monitor layouts and enable/disable output. My panel is a simple horizontal one at the bottom with 100% width and set to remain on the Primary output. "Don't reserve space on borders" is disabled, e.g. it should reserve space.
When switching back to a one-monitor layout (laptop-only), with only one output connected and enabled, it often happens that the panel breaks. It will not reserve space around it anymore, causing maximized windows to extend behind the panel. Toggling "Don't reserve space on borders" does not fix the problem, neither does restarting the panel, or Xfwm4.
At this point I'm not sure which component is responsible for this bug.
Curious. once this bug appears, I can move the panel from the bottom to the top, and it WILL correctly reserve space there! When I move it to the bottom again, it still fails to do so.
I have figured it out. This is a Xfwm4 bug.
1) Have a panel at the bottom set to remain on the Primary output and to reserve space on borders
2) Have one output active where the panel resides on, e.g. 1920x1080
3) Set the framebuffer size larger than this output, e.g. xrandr --fb 1920x1440
4) Restart Xfwm4
Bug: Xfwm4 assumes 1440 to be the bottom of the display. It should use the output size instead, which still is 1080.
5) Reduce the framebuffer size back to actual output size: xrandr --fb 1920x1080
Bug: Xfwm4 does not notice this change, and is stuck at 1440 until restarted.
ccing relevant developer
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