These might help you out.
https://stackoverflow.com/questions/...corated-window
https://stackoverflow.com/questions/...indows-borders
Is it possible to change a programs colour outline (JavaFX)
My program
Shit like steam you dont see that and chrome, how would I go about it?
These might help you out.
https://stackoverflow.com/questions/...corated-window
https://stackoverflow.com/questions/...indows-borders