ActionScript 3 :: Controlling Two Different Shapes With Mouse Events

I'm attempting to control 2 different shapes (a red rectangle and a blue rectangle) with the same sequence of mouse events (down, move, up), but only one shape at a time must move. The shapes are locked horizontally along the x-axis. The red rectangle, which starts out on the left side of the stage, has a right-registration while the the blue rectangle on the right side of the stage has a left-registration.

The rectangle that moves during the MOUSE_MOVE events is the shape that is closest to the *MOUSE_MOVE* event's stageX property. The closest rectangle is determined by averaging the x property of each rectangle (averageX)in relation to the MOUSE_MOVE stageX property. Therefore, if stageX is less than averageX, the shape on the left should move. Greater than averageX, the shape on the right.

The problem occurs when control changes rectangles during subsequent MOUSE_MOVE events, before MOUSE_UP. Variables that are set during MOUSE_DOWN are appropriate for the rectangle that is moved first, but things become dicey when the other rectangle is to be moved instead. Basically, the rectangle whose x property is closest to MOUSE_MOVE event's stageX property should move along either left or right with the mouse event, one at a time.

For simplicity with the following code example, a MOUSE_DOWN event could always occur somewhere between the two rectangles.
package{
import flash.display.Sprite;
import flash.display.Shape;
import flash.events.MouseEvent;
[Code] .....