Rectangle.as

// emptyMovieClip as a MovieClip - x & y at 0 
// Rectangle( x, y, width, height )

var currentRect:Rectangle = new Rectangle( 0, 0, 50, 50 );
var mc:MovieClip = emptyMovieClip.createEmptyMovieClip("mc", emptyMovieClip.getNextHighestDepth());

drawRectangle( mc, currentRect.x, currentRect.y, currentRect.width, currentRect.height, 0x000000, 100, 1, 0x000000, 100 );

private function drawRectangle(mc:MovieClip, rectX:Number, rectY:Number, rectWidth:Number, rectHeight:Number, fillColor:Number, fillAlpha:Number, lineThickness:Number, lineColor:Number, lineAlpha:Number) 
{
    mc.clear();

    with (mc) 
    {
        beginFill(fillColor, fillAlpha);
        lineStyle(lineThickness, lineColor, lineAlpha);
        moveTo(rectX, rectY);
        lineTo(rectX, rectY + rectHeight);
        lineTo(rectX + rectWidth, rectY + rectHeight);
        lineTo(rectX + rectWidth, rectY);
        endFill();
    }
}