@Gama11 Thanks Gama11,

But that will treat the sprite as a rectangular box, so it's not accurate for complex shapes.

I attached a screenshot. Is it possible to make the areas with magenta color invisible and still detect when the mouse is over them?

I created some FlxSprites and loaded some images, and I set their alpha to 0. I want to use them as mouse hit areas in my game. How do I trigger onMouseOver events on those transparent sprites? At the moment to make it work I have to set alpha to 0.1, but I want to make the sprites totally invisible. Is that possible? Thanks!