I've noticed that when you hover the mouse over a button, it highlights while the button is off. However when the button is on, it doesn't highlight. This is ok for normal buttons. But when you use BUTTON_STAY and the button is on, then it no longer highlights when moving the mouse over it. Because of this, the user no longer realises that it is an active button they can click (especially when using a custom image so it doesn't look exactly like a button).

I recommend using custom virtual draw