After some further investigation, I have found the following workarounds to this issue.
The problem seems to be coming from the Raspberry PI desktop (Rasbian) trying to my best guess assert itself.
The screen resolution of the display I am using is 1280x800. At the top of the main module the default statement for the main forms is
#VirtualMachineArgs: -Djavafx.platform=Monocle
#MainFormWidth: 1280
#MainFormHeight: 800
If I change either the main for height of the main form width by one pixel - 1279 or 799, the problem goes away. The issue then is that the toolbar for the Raspbian desktop then shows itself at the top of the page, which is somewhat undesired in this case. Also in this case the frm.AwaysOnTop = True seems to work fine.
Another workaround I discovered, is to use in the called module, to show a form, instead of frm.Show, use frm.ShowAndWait.
I am not that familiar with this command and don't know if there are any implications to using this instead, just stumbled across it by accident.
When using that command, there is a side affect in terms of the screen, in this case touching outside the shown form, at least does not collapse the form into the background of the main form making it invisible, instead it quickly flashes the entire screen (like the screen is redrawing itself), though a bit noticeable, it is a compromise I can live with for the moment unless there's a better solution.