code:

on the mc whose size you want to change:

onClipEvent (enterFrame) {
xdist = this._parent._xmouse - this._x
xdist2 = this._parent._xmouse - this._x
if (this.hitTest (_root.moosboy)) {
if (this._parent._xmouse < this._x) {
this._yscale = 100 + xdist/2;
this._xscale = 100 + xdist/2;
} else if (this._parent._xmouse >= this._x) {
this._yscale = 100 - xdist2/2;
this._xscale = 100 - xdist2/2;
}
}
}

moosboy is an mc that follows the mouse which cover all the screen for the first second or so, then stop and decrease it's size to about W:164.8 H:doesn't matter as long as it can touch the mc's you want to change size.

put this code on moosboy:

onClipEvent (enterFrame) {
this._x = this._parent._xmouse;
}

just make sure all of these mc's are on the same layer and it should work out.