Big big big big SORRY for late answer.
(and sorry for my english)
HERE is the .capx
It's very simple:
On Start every object spawns the shadow-sprite.
Every tick the shadow-sprite's width and height will set to an special value (distance between mouseX,Y and shadow-sprite). Also will look into direction of mouxeX,Y (or wherever the light is).
But it's NOT REAL Light&Shadow, it's more faked, but can be useful ;)