Draw Line tool like flash line tool

programming flash
1

I want to create a line tool exactly like flash line tool. But the code that I am using shows the line when we release the mouse button. How can I show the lines while it is drawing

this.createEmptyMovieClip("drawing_mc",this.getNextHighestDepth());
drawing_mc.lineStyle(1,100);

this.onMouseDown = function() {
    drawing_mc.moveTo(_xmouse,_ymouse);
};

this.onMouseUp = function() {
    drawing_mc.lineTo(_xmouse,_ymouse);
};