Hey,
I tried the xaml code that you supplied, but for me it does not work because I must have the scenic style as false to have a circle button with an image inside of it.
It works to get the Image by using GetTemplateChild("PART_ApplicationIcon") as you said, and it works to hide it correctly.
But when I hide it, its behaviour is still functioning, for example, if you double click that area that it was in, the application closes, and if you click on that area just once, a default popup behaviour is executed. Is there some way to remove this behaviour?
Cheers,
Tommy