Weird window behaviour - Help

Have a window that when you click Full screen button it switches to a full screen but the window collapses into the top of screen and leaves a black window. If I go back to the Main menu and click the button for that window, it takes me to the full screen black window.

If I move the cursor to the edge of the window, it just shows the arrow pointing in and if I click it the window closes. I can not figure out what is happening.

I put breakpoints in the various events for the window but it doesn’t reveal what’s happening.

I have Close Button, Maximise button Fullscreen and Resizeable enabled on the window. Window is Document type.


When I hover over the green button It shows a menu

Enter Full Screen
Tile window to left of screen
Tile window to right of screen

I can’t find any 3rd party apps that might be causing this.

Other screens in app behave as expected.

Other screens show same menu when I hover over green button.

In Fact all windows from all apps do.

the menu is nomal for catalina (maybe earlier versions as well)

I am on Catalina, But why is it only affecting this one window like this?

Problem solved, The minimum and Maximum window sizes were set to zero. Changed that and it now works.

is this a project brought forward from an older version of Xojo and it same across with those values all set to 0 ?

Other windows have values, but it has gone through multiple generations of xojo.