Up till now, I've always created a target drop area by using 4 coordinates. My question to you is, in AS2 and/or AS3 is it possible to do the same thing but with radius and the area of a circle? This seems like it could save me a lot of time because there would only be 1 variable. Would this be more taxing on the users computer?

[Isocase]

You could use

public function getBounds(targetCoordinateSpace:DisplayObject):Rectangle

to get the area of the circle. Hopefully that will help you out and is what you were looking for.

[BSMH]

I'm sorry Isocase. I guess I didn't make what I'm looking for clear.
Rather than typing something like:

If (mouse.x is <= -32 && mouse.x >= 32 && mouse.y <= -32 && mouse.y >= 32)

I thought there might be a way to dynamically create the same above but with a circle (surrounding an MC) with a set radius. The sole purpose of this circle is (like above) to test if the cursor is inside it to trigger an event. That way I only have to set a radius rather than 4 numbers like the above code. Plus I wouldn't have to keep track of whether a number is negative or positive. Just how wide from the center (radius) I want the circle to be.

[BSMH]

Well, I had to get my old Trig math book out, but I figured it out. After thinking about it I realize how simple it really is. The mc on the stage is called CenterCirc.

var radDistance = 5000;

this.onEnterFrame = function() {

	if (distF(CenterCirc)) {
		var cursorDist = Math.round(distF(CenterCirc));

		if (cursorDist<=radDistance) {
			trace("inside circle");
		};
	};

	function distF(CenterCirc):Number {
		return (CenterCirc._x-_xmouse)*(CenterCirc._x-_xmouse)+(CenterCirc._y-_ymouse)*(CenterCirc._y-_ymouse);
	};

};

With this I only have to worry about the radDistance variable. No need to create a perimeter box and calculate negative numbers. I used the Pythagorean theorem to make this work. Essentially this calculates the hypotenuse of a triangle created by the center of the mc and the cursors x y coordinates.