I'm having this situation:
I often use windows outside the screen for doing things in scripts without disturbing the active layout. When debugging I sometimes need to make such a window visible again, so I have in the scripts menu some tools-scripts like "Make active window visible" amongst others.
Works fine, mostly, but sometimes the whole scripts-menu is not accessible while debugging and I can't figure out why.
Even with the same active layout.
I like to use a global variable $$env (environment) that I set to 'dev' for testing. Then all my scripts have IF conditions around common actions like; window position or perform script (locally or server side).
The Scripts-menu is not visible for the users because I use custom menus.
My question is not how to see the new window (I know the techniques you describe) but why is the scripts-menu with the same layout sometimes not accessible?
What version of FileMaker are you using? I believe there is a combination of steps involving Freeze Window and Create New Window then Close Window, where the new window never is actually displayed, which means you may not need to create the window offscreen?
Edit to add: I think perhaps the secret is to make the new window a Card Window style? It's been awhile since I programmed this so I may be misremembering...