var SlidingTabs = new Class({
   Implements: [Options,Events],
   options: {
     startingSlide: false, // sets the slide to start on, either an element or an id
     activeButtonClass: 'active', // class to add to selected button
     activationEvent: 'click', // you can set this to ÔmouseoverÕ or whatever you like
     wrap: true, // calls to previous() and next() should wrap around?
     slideEffect: { // options for effect used to animate the sliding, see Fx.Base in mootools docs
       duration: 400 // 0.4 of a second
     },
     animateHeight: true, // animate height of container
     rightOversized: 0 // how much of the next pane to show to the right of the current pane
   },
   current: null, // zero based current pane number, read only
   buttons: false,
   outerSlidesBox: null,
   innerSlidesBox: null,
   panes: null,
   fx: null, // this one animates the scrolling inside
   heightFx: null, // this one animates the height
   initialize: function(buttonContainer, slideContainer, options) {
   if (buttonContainer) { this.buttons = $(buttonContainer).getChildren(); };
     this.outerSlidesBox = $(slideContainer);
     this.innerSlidesBox = this.outerSlidesBox.getFirst();
     this.panes = this.innerSlidesBox.getChildren();
     this.setOptions(options);
     this.fx = new Fx.Scroll(this.outerSlidesBox, this.options.slideEffect);
     this.heightFx = this.outerSlidesBox.set('height', this.options.slideEffect);
     // set up button highlight
     this.current = this.options.startingSlide ? this.panes.indexOf($(this.options.startingSlide)) : 0;
     if (this.buttons) { this.buttons[this.current].addClass(this.options.activeButtonClass); };
    
     // add needed stylings
     this.outerSlidesBox.setStyle('overflow', 'hidden');
     this.panes.each(function(pane, index) {
     pane.setStyles({
        'float': 'left',
        'display':'block',
        'overflow': 'hidden'
      });
   }.bind(this));
     // stupidness to make IE work - it boggles the mind why this has any effect
     // maybe it's something to do with giving it layout?
    this.innerSlidesBox.setStyle('float', 'left');
    
    if (this.options.startingSlide) {this.fx.toElement(this.options.startingSlide);};
   
     // add events to the buttons
     if (this.buttons) this.buttons.each( function(button) {
     button.addEvent(this.options.activationEvent, this.buttonEventHandler.bindWithEvent(this, button));
     }.bind(this));
    
     if (this.options.animateHeight){
       this.heightFx.tween('height',this.panes[this.current].offsetHeight);
     };
    
     // set up all the right widths inside the panes
     this.recalcWidths();
   },
 
  // to change to a specific tab, call this, argument is the pane element you want to switch to.
   changeTo: function(element, animate) {
   if ($type(element) == 'number') {element = this.panes[element - 1];};
   if (!$defined(animate)) {animate = true;};
     var event = { cancel: false, target: $(element), animateChange: animate };
     this.fireEvent('change', event);
     if (event.cancel == true) { return; };
   
     if (this.buttons) { this.buttons[this.current].removeClass(this.options.activeButtonClass); };
     this.current = this.panes.indexOf($(event.target));
     if (this.buttons) { this.buttons[this.current].addClass(this.options.activeButtonClass); };
    
    this.fx.cancel();
    if (event.animateChange) {
       this.fx.toElement(event.target);
    } else {
      this.outerSlidesBox.scrollTo(this.current * this.outerSlidesBox.offsetWidth.toInt(), 0);
  };
    
       //if (this.options.animateHeight);
       //this.heightFX.set({
       //height:this.panes[this.current].offsetHeight,
       //});
      
       if (this.options.animateHeight){
       this.heightFx.tween('height',this.panes[this.current].offsetHeight);
       };
   },
  
  
   // Handles a click
   buttonEventHandler: function(event, button) {
     if (event.target == this.buttons[this.current]) {return;};
     this.changeTo(this.panes[this.buttons.indexOf($(button))]);
   },
  
   // call this to go to the next tab
   next: function() {
     var next = this.current + 1;
     if (next == this.panes.length) {
       if (this.options.wrap == true) { next = 0 } else { return };
     };
    
     this.changeTo(this.panes[next]);
   },
  
   // to go to the previous tab
   previous: function() {
     var prev = this.current - 1
     if (prev < 0) {
       if (this.options.wrap == true) { prev = this.panes.length - 1 } else { return };
     };
    
     this.changeTo(this.panes[prev]);
   },
  
   // call this if the width of the sliding tabs container changes to get everything in line again
   recalcWidths: function() {
     this.panes.each(function(pane, index) {
       pane.setStyle('width', this.outerSlidesBox.offsetWidth.toInt() - this.options.rightOversized + 'px');
     }.bind(this));
    
     this.innerSlidesBox.setStyle(
       'width', (this.outerSlidesBox.offsetWidth.toInt() * this.panes.length) + 'px'
     );
    
     // fix positioning
     if (this.current > 0) {
       this.fx.cancel();
       this.outerSlidesBox.scrollTo(this.current * this.outerSlidesBox.offsetWidth.toInt(), 0);
     };
   }
 });
 
 SlidingTabs.implement(new Options, new Events);