Windows.Frame Type different on Windows and Mac

I know that Windows.Frame is a property that can only be set in the Inspector and is not available in code, but is there any chance to set it different for a windows compilation than on a Mac one in order to have the same code for both enviroments and use the #If TargetWindows comand ?
I want to have Sheet Window on Mac and a Modal dialog on Windows to avoi the windows title area… Is that possible by any trick anyone knows ?

Sheet windows behave as such only on OS X. On other platforms, they behave as ordinary movable modal dialog boxes.

IF you could assign a constant for the frame type that constant could have different values for macOS and Windows
But thats not possible

But, as Dave notes, if you make this a sheet window then on non-Mac platforms it will be a movable modal - the closest equivalent Windows has for a sheet.

Thanks to both of you, Norman and Dave.