IsMouseOver trigger doesn't work when using ShowDialog and borderless window

Question

I have two Windows for an application. One of them is MainWindow and the other is for settings. SettingsWindow opens when settings but

Answer 1

This works for me: Define a style resource (for the button) under settings Window.Resources - This style then sets the new Template (a border), the default background as blue, and the IsMouseOver trigger to change it to red. Reference the style either explicitly for implicitly (both worked for me).

Link to small test project: https://1drv.ms/u/s!AhlMAmchX3R6nDJ1MXS6DxlRXtnA