Scrolling a Pane to the Top of a Flash Movie

Here is the code inside the scroll button:

onClipEvent (load)
{
 oldY = 1;
 Y = 1;
 vY = 0;
 newY = 0;
 mouseWheelHitTest = true;
 contentHeight = _parent.scrolledMC._height;
 scrollSpeed = _parent.speed_content;
 scrollStep = _parent.step_content;
 viewHeight = _parent.line._height;
 buttonSize = _parent.dragMC._height;
 buttonY = buttonMC._y;
 scrollHeight = _parent.scrolledMC._height + 875;
 scrollContent = _parent.scrolledMC._y;
 scrollContent1 = _parent.scrolledMC;
 newY = _parent.scrolledMC._height;
 var mouseListener:Object = new Object();
 mouseListener.onMouseWheel = function(delta)
 {
  if (!mouseWheelHitTest || scrollContent1.hitTest(_root._xmouse, _root._ymouse, false) || hitTest(_root._xmouse, _root._ymouse, false))
  {
   if (buttonMC._y>=0 && buttonMC._y<=scrollHeight-buttonSize+1)
   {
    buttonMC._y -= (delta)*_parent.mouse_speed;
   }
  }
 };
 Mouse.addListener(mouseListener);
 hiScroll = _parent.line._height-_parent.dragMC._height;
 step = ((scrollHeight-buttonSize)-(hiScroll))/(hiScroll);
 y = _parent.scrolledMC._y;
}
onClipEvent (enterFrame)
{
 if (_parent.drag_but)
 {
  if (buttonMC._y>=0)
  {
   buttonMC._y -= scrollStep;
  }
 }
 
 if (_parent.down_but)
 {
  if (buttonMC._y<=scrollHeight+buttonSize)
  {
   buttonMC._y += scrollStep;
  }
 }
 
 if (buttonMC._y<=0)
 {
  buttonMC._y = 0;
 }
 
 if (buttonMC._y>=viewHeight-buttonSize)
 {
  buttonMC._y = viewHeight-buttonSize;
 }
 
 level = buttonMC._y-buttonY;
 lev = int(y-(level*step));
 newY = oldY+(lev-oldY)/scrollSpeed;
 _parent.scrolledMC._y = newY;
 oldY = newY;
}

And here is code on the top of the frame for the pane:

mouse_speed = 2;
speed_content = 6;
step_content = 10;
step = 5;
scrolledMC.setMask(mask);
stop();