Oh yes… many/most/all Xojo Developers that have to deal with TargetWindows and MultiMonitor / MultiScale. Let’s just say that the Xojo Framework is not handling this as expected, not to say it’s broken (for that kind of situation / environment).
This “FullScreen” issue is reported here: <https://xojo.com/issue/64805>
And of course quite some other Feedback Issues regarding MultiMonitor/MultiScale on Windows…
Do the positioning yourself using Declares and don’t rely on the Xojo Framework (for now)…
There is this example project: Monitors
Back to you “FullScreen” issue… have a look at the updated “Monitors - example” that I’ve attached in <https://xojo.com/issue/64805> on June 22, 2021.
I haven’t had time to clean up the “FullScreen” quick-and-dirty test and update the example project “Monitors example” version on my website… so for “FullScreen”, have a look at the one in Feedback for now.