Overwritten variable, thumbnail scroll panel

Question

I'm building a website with several menu options. I use thumbnail panel scroll examples and modified it to achieve what I want to do. Loading dynamically each photography items.

Ex: Book 1 ==> Loading 5 images Book 2 ==> Loading 2 images ...

As matter of fact, when clicking Book 1 the total width is larger than Book 2.

The problem is I want to put a limit at the last photo item to stop scrolling further. It seems that my container.panelMC.width is overwritten the last variable all the time. How can I reset it each time which loading different photo gallery?

However Adding the limit in first image index is working fine.

private function handleScroll(event:Event):void 
 {
  var xSpeed  = 0;
  var thumbX  = scrollbarMC.getThumbX();
  var thumb   = scrollbarMC.getThumbMC();
  var trackWidth = scrollbarMC.getTrackMC();
  var bounds  = container.strokeMC.getBounds(this);
  var tempo  = 0;


  // Verify 4 areas when mouse in Outside of the Panel area defined  
  if ((stage.mouseX < bounds.x) || (stage.mouseX > bounds.width) || (stage.mouseY < stage.stageHeight - HEIGHT) || (stage.mouseY > bounds.height)) {

   // Reinstate mouseOver, make sure not to run when outside of panel
   container.panelMC.addEventListener(MouseEvent.MOUSE_OVER, handleTestScroll);
   container.panelMC.removeEventListener(Event.ENTER_FRAME, handleScroll);
  } else {
   // Get the speed distance of X axis
   xSpeed = -(stage.mouseX - middle) / SPEED;

   tempo = container.panelMC.width;
   trace("****Panel Width: "+tempo);

   // From middle stage, verify when mouse is oriented to right side of stage 
   if (stage.mouseX > middle) {
    trace('__Scrolling Right side...');     
    // Add a limit at LAST image index in panel to stop scrolling further
    if (container.panelMC.x >= (stage.stageWidth - tempo)) 
     container.panelMC.x += xSpeed;
   } else {
    trace('__Scrolling Left side: '+stage.x);
    // Add a limit at FIRST image index of container to stop scrolling further
    if (container.panelMC.x < stage.x)   
     container.panelMC.x += xSpeed;
   }

  }
 }