Serial Monitor may not display if the number of real monitors has changed or their placement has changed

I'm working with Windows 10. I have two monitors. Originally my secondary monitor was above my primary monitor. I typically have my serial monitor on the secondary monitor. I rearranged my monitors to have the secondary monitor to the left of the primary monitor. I made the change in Windows 10 Display settings to reflect the new position of the secondary monitor. When I tried to open a Serial Monitor nothing was shown.

I had to change my Display settings back to showing the secondary monitor over the primary. When I did that the Serial Monitor again was shown.

I have seen (and fixed) this problem before with a Java GUI. When showing a secondary panel where you have remembered its previous location you may wind up showing it off the real monitor space. The fix is to make sure the location that was remembered is still a valid location on the available monitors and the title bar at least is shown so that you can grab the panel and move it.

Start by reproducing the Serial Monitor display failure after changing the monitor arrangement in Windows 10. Inspect how the Java GUI remembers and restores the Serial Monitor location, then verify that it remains accessible after monitor count or placement changes. Done means the Serial Monitor opens visibly in the changed display layout.

Written by the indexing model from the issue text.