Create a sprite with a mask effect (PS 0.0), appereance invisible on "start".
Create a canvas on the same position of the sprite.
Bring to the front the sprite.
Create this event:
Always/Start of layout/on click, etc...
+Canvas: paste sprite into canvas
+Canvas: update collision mask
Watch the preview and the effect will be applied only if the sprite pixel opacity is >0.
Construct 99.9