My main screen on the laptop is 1024x768.  I plug in a VGA monitor
which is 1360x768.  I had to use ARandR to activate it BTW, it could
not be activated from Display settings app.

I configured the VGA monitor to appear to the right of the main screen.

The panels are still on the laptop monitor.  Compositor is on with alpha.
There is a top panel with menu, window buttons, clock, etc.  It is 1024
wide and stretches the length of the laptop screen only.

When I unplug the external monitor, the top panel resizes to 1360 wide
and stretches off the edge of the laptop screen.

This happens whether or not autohide is turned on.

When I plug the external monitor back in, the top panel resizes to
1024 wide and fits correctly in the laptop screen.

Thanks.

Mark

Correction.  I could activate the second monitor using the Display
settings app, but the default setting was mirrored display.  I had to
use ARandR to set the VGA monitor to the right side of the laptop
screen.

Mark