OK, so either nobody has had this problem ever, or nobody wants to answer:):)

Usually when I move a pop-up panel to a given position it reappears there when it becomes active. The exception are those that always appear at the center of the screen. When I used to use two screens, those latter panels were a problem whenever I spread my Finale file over both screens because the centered panel would split across the screens.

One thing to check would be the resolution of your display screen. If set correctly the active screenspace could be extending past the border of your physical monitor. No idea if splitting your screen could be contributing to the problem. Needless to say, you ought to be able to use a split screen without losing pop-up panels.

Thanks.

Your advice made me take a break from engraving and try some things.

It does seem that there is a bit of active screen space off both right and left edges of my screen.

But this seems to exist on my laptop's built in monitor as well. And changing resolutions just made the display quality deteriorate.

So I tried this....moved Finale window to the laptop and unplugged my extended monitor from the HDML port.

Then opened a file, moved the tremolo plug-in box from the edge of the screen to the middle, closed it.

Plugged in extended monitor, moved Finale back to it...ran the plug-in.

Voila - box appears in centre.

Thanks for the ideas. Much appreciated.