Changing Colors while Mouse Draging

1

I wanna make a test movie for lets say… a circle dragged by the mouse and changing colors of the circle to certain colors when like on the right top of the stage the circle would be 100% alpha with a color of like blue, on the bottom left it would be 0% alpha with a color of like green or something like that… any ideas… i’m a sorta beginner with actionscript…although i have made many cool things with flash (menus, intros, etc.)