Hi Matthew D.,
I am not sure because not tested, you can test it
In the place of my_icon try to use the virtual path with icon image name or signing jar file contains the icons may work.
Just have a try with the Registry.dat file also.
Try to pass the pass only the icon name my_icon is correct my_icon.ico is wrong.
Check this link may help you. https://www.experts-exchange.com/questions/20937528/Changing-Forms-Runtime-Icon.html
Hope it solves your issue.
this is from forms help:
In normal operation (USESDI=YES parameter is not passed to the application), Forms run inside an MDI application window which may be represented by the Applet are in the HTML page or a separate window if the separateFrame applet parameter has ben set to True.
You can use SET_WINDOW_PROPERTY to set the following properties of the MDI application window:
So, we can't set icon for mdi window.
We can assign icon through set_window_property like this
SET_WINDOW_PROPERTY('Your_window_name_here', ICON_NAME, 'icon file name only');