If you're using AS2, you can use the MovieClip.swapDepths() method to move one clip in front of the other. The clips will need some solid fill, though, otherwise you'll see right through them!
For example:
//Make two clips:
this.createEmptyMovieClip("clip1", 1);
this.createEmptyMovieClip("clip2", 2);
//Draw a coloured rectangle in each:
drawRect(clip1, 0xFF0000);
clip1._x = 50;
clip1._y = 50;
drawRect(clip2, 0x0000FF);
//Add a mouseclick handler
//(you could change this to a keypress handler)
clip1.onRelease = function() {
//SWAP THE DEPTHS OF TWO CLIPS:
clip1.swapDepths(clip2);
};
clip2.onRelease = function() {
clip2.swapDepths(clip1);
};
function drawRect(mc, colour) {
mc.beginFill(colour);
mc.moveTo(100, 100);
mc.lineTo(100, 200);
mc.lineTo(200, 200);
mc.lineTo(200, 100);
mc.lineTo(100, 100);
mc.endFill();
}