Custom mouse pointer rotation is erratic

[Trugas]

Ok well I'm not really replacing the mouse cursor exactly. Just placing a custom image of a pointer below it so it will follow the mouse cursor as it moves around the screen. I want this pointer image to move with the mouse and to rotate and point in the direction the mouse is traveling. Simple stuff.

The problem is that the rotation of the pointer graphic is not smooth at all. It is jumpy and somewhat erratic particularly at slower mouse speeds. When the mouse is moving quickly the problem seems to go away.

What is going on here?

package {
    import flash.display.Sprite;
    import flash.events.*;
    
    public class MouseFollower extends Sprite {
        private var pointer:Pointer = new Pointer(); // ...a simple triangle mc
        
        public function MouseFollower() {
            addChild(pointer);
            stage.addEventListener(MouseEvent.MOUSE_MOVE, enterFrameHandler);
        }
        
        private function enterFrameHandler(moved:MouseEvent):void {    
            var dx:Number = mouseX - pointer.x;
            var dy:Number = mouseY - pointer.y;
            var angle:Number = Math.atan2(dy, dx) * (180/Math.PI);

            pointer.rotation = angle;
            pointer.x = mouseX;
            pointer.y = mouseY;
        }
    }
} 

[Trugas]

Ok, so to explain exactly what I'm seeing: The movieclip graphic following under the mouse is not rotating smoothly. What actually appears to be happening is that the graphic is snapping to 45 degree increments at slow speeds. This only gives eight steps in a rotation. Again, this only happens when the mouse is moving slowly.

When the mouse is moving in a direction that is not exactly horizontal, vertical or diagonal it flickers between the nearest two of these directions.

[Trugas]

Ok I think I found the problem. Mouse coords are only integers not numbers. This lack of precision means that the smallest distance the mouse can move on the x or y axis is exactly 1 px (or -1px), of course it can also not move at all (0 px). These values can only give eight solutions (left, right, up, down and the four diagonals). So the graphic will only point in one of these eight directions when the mouse is moving very slowly.

Any ideas about how I can get around this?