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diff --git a/js/script.aculo.us/dragdrop.js b/js/script.aculo.us/dragdrop.js
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+++ b/js/script.aculo.us/dragdrop.js
@@ -0,0 +1,974 @@
+// script.aculo.us dragdrop.js v1.9.0, Thu Dec 23 16:54:48 -0500 2010
+
+// Copyright (c) 2005-2010 Thomas Fuchs (http://script.aculo.us, http://mir.aculo.us)
+//
+// script.aculo.us is freely distributable under the terms of an MIT-style license.
+// For details, see the script.aculo.us web site: http://script.aculo.us/
+
+if(Object.isUndefined(Effect))
+  throw("dragdrop.js requires including script.aculo.us' effects.js library");
+
+var Droppables = {
+  drops: [],
+
+  remove: function(element) {
+    this.drops = this.drops.reject(function(d) { return d.element==$(element) });
+  },
+
+  add: function(element) {
+    element = $(element);
+    var options = Object.extend({
+      greedy:     true,
+      hoverclass: null,
+      tree:       false
+    }, arguments[1] || { });
+
+    // cache containers
+    if(options.containment) {
+      options._containers = [];
+      var containment = options.containment;
+      if(Object.isArray(containment)) {
+        containment.each( function(c) { options._containers.push($(c)) });
+      } else {
+        options._containers.push($(containment));
+      }
+    }
+
+    if(options.accept) options.accept = [options.accept].flatten();
+
+    Element.makePositioned(element); // fix IE
+    options.element = element;
+
+    this.drops.push(options);
+  },
+
+  findDeepestChild: function(drops) {
+    deepest = drops[0];
+
+    for (i = 1; i < drops.length; ++i)
+      if (Element.isParent(drops[i].element, deepest.element))
+        deepest = drops[i];
+
+    return deepest;
+  },
+
+  isContained: function(element, drop) {
+    var containmentNode;
+    if(drop.tree) {
+      containmentNode = element.treeNode;
+    } else {
+      containmentNode = element.parentNode;
+    }
+    return drop._containers.detect(function(c) { return containmentNode == c });
+  },
+
+  isAffected: function(point, element, drop) {
+    return (
+      (drop.element!=element) &&
+      ((!drop._containers) ||
+        this.isContained(element, drop)) &&
+      ((!drop.accept) ||
+        (Element.classNames(element).detect(
+          function(v) { return drop.accept.include(v) } ) )) &&
+      Position.within(drop.element, point[0], point[1]) );
+  },
+
+  deactivate: function(drop) {
+    if(drop.hoverclass)
+      Element.removeClassName(drop.element, drop.hoverclass);
+    this.last_active = null;
+  },
+
+  activate: function(drop) {
+    if(drop.hoverclass)
+      Element.addClassName(drop.element, drop.hoverclass);
+    this.last_active = drop;
+  },
+
+  show: function(point, element) {
+    if(!this.drops.length) return;
+    var drop, affected = [];
+
+    this.drops.each( function(drop) {
+      if(Droppables.isAffected(point, element, drop))
+        affected.push(drop);
+    });
+
+    if(affected.length>0)
+      drop = Droppables.findDeepestChild(affected);
+
+    if(this.last_active && this.last_active != drop) this.deactivate(this.last_active);
+    if (drop) {
+      Position.within(drop.element, point[0], point[1]);
+      if(drop.onHover)
+        drop.onHover(element, drop.element, Position.overlap(drop.overlap, drop.element));
+
+      if (drop != this.last_active) Droppables.activate(drop);
+    }
+  },
+
+  fire: function(event, element) {
+    if(!this.last_active) return;
+    Position.prepare();
+
+    if (this.isAffected([Event.pointerX(event), Event.pointerY(event)], element, this.last_active))
+      if (this.last_active.onDrop) {
+        this.last_active.onDrop(element, this.last_active.element, event);
+        return true;
+      }
+  },
+
+  reset: function() {
+    if(this.last_active)
+      this.deactivate(this.last_active);
+  }
+};
+
+var Draggables = {
+  drags: [],
+  observers: [],
+
+  register: function(draggable) {
+    if(this.drags.length == 0) {
+      this.eventMouseUp   = this.endDrag.bindAsEventListener(this);
+      this.eventMouseMove = this.updateDrag.bindAsEventListener(this);
+      this.eventKeypress  = this.keyPress.bindAsEventListener(this);
+
+      Event.observe(document, "mouseup", this.eventMouseUp);
+      Event.observe(document, "mousemove", this.eventMouseMove);
+      Event.observe(document, "keypress", this.eventKeypress);
+    }
+    this.drags.push(draggable);
+  },
+
+  unregister: function(draggable) {
+    this.drags = this.drags.reject(function(d) { return d==draggable });
+    if(this.drags.length == 0) {
+      Event.stopObserving(document, "mouseup", this.eventMouseUp);
+      Event.stopObserving(document, "mousemove", this.eventMouseMove);
+      Event.stopObserving(document, "keypress", this.eventKeypress);
+    }
+  },
+
+  activate: function(draggable) {
+    if(draggable.options.delay) {
+      this._timeout = setTimeout(function() {
+        Draggables._timeout = null;
+        window.focus();
+        Draggables.activeDraggable = draggable;
+      }.bind(this), draggable.options.delay);
+    } else {
+      window.focus(); // allows keypress events if window isn't currently focused, fails for Safari
+      this.activeDraggable = draggable;
+    }
+  },
+
+  deactivate: function() {
+    this.activeDraggable = null;
+  },
+
+  updateDrag: function(event) {
+    if(!this.activeDraggable) return;
+    var pointer = [Event.pointerX(event), Event.pointerY(event)];
+    // Mozilla-based browsers fire successive mousemove events with
+    // the same coordinates, prevent needless redrawing (moz bug?)
+    if(this._lastPointer && (this._lastPointer.inspect() == pointer.inspect())) return;
+    this._lastPointer = pointer;
+
+    this.activeDraggable.updateDrag(event, pointer);
+  },
+
+  endDrag: function(event) {
+    if(this._timeout) {
+      clearTimeout(this._timeout);
+      this._timeout = null;
+    }
+    if(!this.activeDraggable) return;
+    this._lastPointer = null;
+    this.activeDraggable.endDrag(event);
+    this.activeDraggable = null;
+  },
+
+  keyPress: function(event) {
+    if(this.activeDraggable)
+      this.activeDraggable.keyPress(event);
+  },
+
+  addObserver: function(observer) {
+    this.observers.push(observer);
+    this._cacheObserverCallbacks();
+  },
+
+  removeObserver: function(element) {  // element instead of observer fixes mem leaks
+    this.observers = this.observers.reject( function(o) { return o.element==element });
+    this._cacheObserverCallbacks();
+  },
+
+  notify: function(eventName, draggable, event) {  // 'onStart', 'onEnd', 'onDrag'
+    if(this[eventName+'Count'] > 0)
+      this.observers.each( function(o) {
+        if(o[eventName]) o[eventName](eventName, draggable, event);
+      });
+    if(draggable.options[eventName]) draggable.options[eventName](draggable, event);
+  },
+
+  _cacheObserverCallbacks: function() {
+    ['onStart','onEnd','onDrag'].each( function(eventName) {
+      Draggables[eventName+'Count'] = Draggables.observers.select(
+        function(o) { return o[eventName]; }
+      ).length;
+    });
+  }
+};
+
+/*--------------------------------------------------------------------------*/
+
+var Draggable = Class.create({
+  initialize: function(element) {
+    var defaults = {
+      handle: false,
+      reverteffect: function(element, top_offset, left_offset) {
+        var dur = Math.sqrt(Math.abs(top_offset^2)+Math.abs(left_offset^2))*0.02;
+        new Effect.Move(element, { x: -left_offset, y: -top_offset, duration: dur,
+          queue: {scope:'_draggable', position:'end'}
+        });
+      },
+      endeffect: function(element) {
+        var toOpacity = Object.isNumber(element._opacity) ? element._opacity : 1.0;
+        new Effect.Opacity(element, {duration:0.2, from:0.7, to:toOpacity,
+          queue: {scope:'_draggable', position:'end'},
+          afterFinish: function(){
+            Draggable._dragging[element] = false
+          }
+        });
+      },
+      zindex: 1000,
+      revert: false,
+      quiet: false,
+      scroll: false,
+      scrollSensitivity: 20,
+      scrollSpeed: 15,
+      snap: false,  // false, or xy or [x,y] or function(x,y){ return [x,y] }
+      delay: 0
+    };
+
+    if(!arguments[1] || Object.isUndefined(arguments[1].endeffect))
+      Object.extend(defaults, {
+        starteffect: function(element) {
+          element._opacity = Element.getOpacity(element);
+          Draggable._dragging[element] = true;
+          new Effect.Opacity(element, {duration:0.2, from:element._opacity, to:0.7});
+        }
+      });
+
+    var options = Object.extend(defaults, arguments[1] || { });
+
+    this.element = $(element);
+
+    if(options.handle && Object.isString(options.handle))
+      this.handle = this.element.down('.'+options.handle, 0);
+
+    if(!this.handle) this.handle = $(options.handle);
+    if(!this.handle) this.handle = this.element;
+
+    if(options.scroll && !options.scroll.scrollTo && !options.scroll.outerHTML) {
+      options.scroll = $(options.scroll);
+      this._isScrollChild = Element.childOf(this.element, options.scroll);
+    }
+
+    Element.makePositioned(this.element); // fix IE
+
+    this.options  = options;
+    this.dragging = false;
+
+    this.eventMouseDown = this.initDrag.bindAsEventListener(this);
+    Event.observe(this.handle, "mousedown", this.eventMouseDown);
+
+    Draggables.register(this);
+  },
+
+  destroy: function() {
+    Event.stopObserving(this.handle, "mousedown", this.eventMouseDown);
+    Draggables.unregister(this);
+  },
+
+  currentDelta: function() {
+    return([
+      parseInt(Element.getStyle(this.element,'left') || '0'),
+      parseInt(Element.getStyle(this.element,'top') || '0')]);
+  },
+
+  initDrag: function(event) {
+    if(!Object.isUndefined(Draggable._dragging[this.element]) &&
+      Draggable._dragging[this.element]) return;
+    if(Event.isLeftClick(event)) {
+      // abort on form elements, fixes a Firefox issue
+      var src = Event.element(event);
+      if((tag_name = src.tagName.toUpperCase()) && (
+        tag_name=='INPUT' ||
+        tag_name=='SELECT' ||
+        tag_name=='OPTION' ||
+        tag_name=='BUTTON' ||
+        tag_name=='TEXTAREA')) return;
+
+      var pointer = [Event.pointerX(event), Event.pointerY(event)];
+      var pos     = this.element.cumulativeOffset();
+      this.offset = [0,1].map( function(i) { return (pointer[i] - pos[i]) });
+
+      Draggables.activate(this);
+      Event.stop(event);
+    }
+  },
+
+  startDrag: function(event) {
+    this.dragging = true;
+    if(!this.delta)
+      this.delta = this.currentDelta();
+
+    if(this.options.zindex) {
+      this.originalZ = parseInt(Element.getStyle(this.element,'z-index') || 0);
+      this.element.style.zIndex = this.options.zindex;
+    }
+
+    if(this.options.ghosting) {
+      this._clone = this.element.cloneNode(true);
+      this._originallyAbsolute = (this.element.getStyle('position') == 'absolute');
+      if (!this._originallyAbsolute)
+        Position.absolutize(this.element);
+      this.element.parentNode.insertBefore(this._clone, this.element);
+    }
+
+    if(this.options.scroll) {
+      if (this.options.scroll == window) {
+        var where = this._getWindowScroll(this.options.scroll);
+        this.originalScrollLeft = where.left;
+        this.originalScrollTop = where.top;
+      } else {
+        this.originalScrollLeft = this.options.scroll.scrollLeft;
+        this.originalScrollTop = this.options.scroll.scrollTop;
+      }
+    }
+
+    Draggables.notify('onStart', this, event);
+
+    if(this.options.starteffect) this.options.starteffect(this.element);
+  },
+
+  updateDrag: function(event, pointer) {
+    if(!this.dragging) this.startDrag(event);
+
+    if(!this.options.quiet){
+      Position.prepare();
+      Droppables.show(pointer, this.element);
+    }
+
+    Draggables.notify('onDrag', this, event);
+
+    this.draw(pointer);
+    if(this.options.change) this.options.change(this);
+
+    if(this.options.scroll) {
+      this.stopScrolling();
+
+      var p;
+      if (this.options.scroll == window) {
+        with(this._getWindowScroll(this.options.scroll)) { p = [ left, top, left+width, top+height ]; }
+      } else {
+        p = Position.page(this.options.scroll).toArray();
+        p[0] += this.options.scroll.scrollLeft + Position.deltaX;
+        p[1] += this.options.scroll.scrollTop + Position.deltaY;
+        p.push(p[0]+this.options.scroll.offsetWidth);
+        p.push(p[1]+this.options.scroll.offsetHeight);
+      }
+      var speed = [0,0];
+      if(pointer[0] < (p[0]+this.options.scrollSensitivity)) speed[0] = pointer[0]-(p[0]+this.options.scrollSensitivity);
+      if(pointer[1] < (p[1]+this.options.scrollSensitivity)) speed[1] = pointer[1]-(p[1]+this.options.scrollSensitivity);
+      if(pointer[0] > (p[2]-this.options.scrollSensitivity)) speed[0] = pointer[0]-(p[2]-this.options.scrollSensitivity);
+      if(pointer[1] > (p[3]-this.options.scrollSensitivity)) speed[1] = pointer[1]-(p[3]-this.options.scrollSensitivity);
+      this.startScrolling(speed);
+    }
+
+    // fix AppleWebKit rendering
+    if(Prototype.Browser.WebKit) window.scrollBy(0,0);
+
+    Event.stop(event);
+  },
+
+  finishDrag: function(event, success) {
+    this.dragging = false;
+
+    if(this.options.quiet){
+      Position.prepare();
+      var pointer = [Event.pointerX(event), Event.pointerY(event)];
+      Droppables.show(pointer, this.element);
+    }
+
+    if(this.options.ghosting) {
+      if (!this._originallyAbsolute)
+        Position.relativize(this.element);
+      delete this._originallyAbsolute;
+      Element.remove(this._clone);
+      this._clone = null;
+    }
+
+    var dropped = false;
+    if(success) {
+      dropped = Droppables.fire(event, this.element);
+      if (!dropped) dropped = false;
+    }
+    if(dropped && this.options.onDropped) this.options.onDropped(this.element);
+    Draggables.notify('onEnd', this, event);
+
+    var revert = this.options.revert;
+    if(revert && Object.isFunction(revert)) revert = revert(this.element);
+
+    var d = this.currentDelta();
+    if(revert && this.options.reverteffect) {
+      if (dropped == 0 || revert != 'failure')
+        this.options.reverteffect(this.element,
+          d[1]-this.delta[1], d[0]-this.delta[0]);
+    } else {
+      this.delta = d;
+    }
+
+    if(this.options.zindex)
+      this.element.style.zIndex = this.originalZ;
+
+    if(this.options.endeffect)
+      this.options.endeffect(this.element);
+
+    Draggables.deactivate(this);
+    Droppables.reset();
+  },
+
+  keyPress: function(event) {
+    if(event.keyCode!=Event.KEY_ESC) return;
+    this.finishDrag(event, false);
+    Event.stop(event);
+  },
+
+  endDrag: function(event) {
+    if(!this.dragging) return;
+    this.stopScrolling();
+    this.finishDrag(event, true);
+    Event.stop(event);
+  },
+
+  draw: function(point) {
+    var pos = this.element.cumulativeOffset();
+    if(this.options.ghosting) {
+      var r   = Position.realOffset(this.element);
+      pos[0] += r[0] - Position.deltaX; pos[1] += r[1] - Position.deltaY;
+    }
+
+    var d = this.currentDelta();
+    pos[0] -= d[0]; pos[1] -= d[1];
+
+    if(this.options.scroll && (this.options.scroll != window && this._isScrollChild)) {
+      pos[0] -= this.options.scroll.scrollLeft-this.originalScrollLeft;
+      pos[1] -= this.options.scroll.scrollTop-this.originalScrollTop;
+    }
+
+    var p = [0,1].map(function(i){
+      return (point[i]-pos[i]-this.offset[i])
+    }.bind(this));
+
+    if(this.options.snap) {
+      if(Object.isFunction(this.options.snap)) {
+        p = this.options.snap(p[0],p[1],this);
+      } else {
+      if(Object.isArray(this.options.snap)) {
+        p = p.map( function(v, i) {
+          return (v/this.options.snap[i]).round()*this.options.snap[i] }.bind(this));
+      } else {
+        p = p.map( function(v) {
+          return (v/this.options.snap).round()*this.options.snap }.bind(this));
+      }
+    }}
+
+    var style = this.element.style;
+    if((!this.options.constraint) || (this.options.constraint=='horizontal'))
+      style.left = p[0] + "px";
+    if((!this.options.constraint) || (this.options.constraint=='vertical'))
+      style.top  = p[1] + "px";
+
+    if(style.visibility=="hidden") style.visibility = ""; // fix gecko rendering
+  },
+
+  stopScrolling: function() {
+    if(this.scrollInterval) {
+      clearInterval(this.scrollInterval);
+      this.scrollInterval = null;
+      Draggables._lastScrollPointer = null;
+    }
+  },
+
+  startScrolling: function(speed) {
+    if(!(speed[0] || speed[1])) return;
+    this.scrollSpeed = [speed[0]*this.options.scrollSpeed,speed[1]*this.options.scrollSpeed];
+    this.lastScrolled = new Date();
+    this.scrollInterval = setInterval(this.scroll.bind(this), 10);
+  },
+
+  scroll: function() {
+    var current = new Date();
+    var delta = current - this.lastScrolled;
+    this.lastScrolled = current;
+    if(this.options.scroll == window) {
+      with (this._getWindowScroll(this.options.scroll)) {
+        if (this.scrollSpeed[0] || this.scrollSpeed[1]) {
+          var d = delta / 1000;
+          this.options.scroll.scrollTo( left + d*this.scrollSpeed[0], top + d*this.scrollSpeed[1] );
+        }
+      }
+    } else {
+      this.options.scroll.scrollLeft += this.scrollSpeed[0] * delta / 1000;
+      this.options.scroll.scrollTop  += this.scrollSpeed[1] * delta / 1000;
+    }
+
+    Position.prepare();
+    Droppables.show(Draggables._lastPointer, this.element);
+    Draggables.notify('onDrag', this);
+    if (this._isScrollChild) {
+      Draggables._lastScrollPointer = Draggables._lastScrollPointer || $A(Draggables._lastPointer);
+      Draggables._lastScrollPointer[0] += this.scrollSpeed[0] * delta / 1000;
+      Draggables._lastScrollPointer[1] += this.scrollSpeed[1] * delta / 1000;
+      if (Draggables._lastScrollPointer[0] < 0)
+        Draggables._lastScrollPointer[0] = 0;
+      if (Draggables._lastScrollPointer[1] < 0)
+        Draggables._lastScrollPointer[1] = 0;
+      this.draw(Draggables._lastScrollPointer);
+    }
+
+    if(this.options.change) this.options.change(this);
+  },
+
+  _getWindowScroll: function(w) {
+    var T, L, W, H;
+    with (w.document) {
+      if (w.document.documentElement && documentElement.scrollTop) {
+        T = documentElement.scrollTop;
+        L = documentElement.scrollLeft;
+      } else if (w.document.body) {
+        T = body.scrollTop;
+        L = body.scrollLeft;
+      }
+      if (w.innerWidth) {
+        W = w.innerWidth;
+        H = w.innerHeight;
+      } else if (w.document.documentElement && documentElement.clientWidth) {
+        W = documentElement.clientWidth;
+        H = documentElement.clientHeight;
+      } else {
+        W = body.offsetWidth;
+        H = body.offsetHeight;
+      }
+    }
+    return { top: T, left: L, width: W, height: H };
+  }
+});
+
+Draggable._dragging = { };
+
+/*--------------------------------------------------------------------------*/
+
+var SortableObserver = Class.create({
+  initialize: function(element, observer) {
+    this.element   = $(element);
+    this.observer  = observer;
+    this.lastValue = Sortable.serialize(this.element);
+  },
+
+  onStart: function() {
+    this.lastValue = Sortable.serialize(this.element);
+  },
+
+  onEnd: function() {
+    Sortable.unmark();
+    if(this.lastValue != Sortable.serialize(this.element))
+      this.observer(this.element)
+  }
+});
+
+var Sortable = {
+  SERIALIZE_RULE: /^[^_\-](?:[A-Za-z0-9\-\_]*)[_](.*)$/,
+
+  sortables: { },
+
+  _findRootElement: function(element) {
+    while (element.tagName.toUpperCase() != "BODY") {
+      if(element.id && Sortable.sortables[element.id]) return element;
+      element = element.parentNode;
+    }
+  },
+
+  options: function(element) {
+    element = Sortable._findRootElement($(element));
+    if(!element) return;
+    return Sortable.sortables[element.id];
+  },
+
+  destroy: function(element){
+    element = $(element);
+    var s = Sortable.sortables[element.id];
+
+    if(s) {
+      Draggables.removeObserver(s.element);
+      s.droppables.each(function(d){ Droppables.remove(d) });
+      s.draggables.invoke('destroy');
+
+      delete Sortable.sortables[s.element.id];
+    }
+  },
+
+  create: function(element) {
+    element = $(element);
+    var options = Object.extend({
+      element:     element,
+      tag:         'li',       // assumes li children, override with tag: 'tagname'
+      dropOnEmpty: false,
+      tree:        false,
+      treeTag:     'ul',
+      overlap:     'vertical', // one of 'vertical', 'horizontal'
+      constraint:  'vertical', // one of 'vertical', 'horizontal', false
+      containment: element,    // also takes array of elements (or id's); or false
+      handle:      false,      // or a CSS class
+      only:        false,
+      delay:       0,
+      hoverclass:  null,
+      ghosting:    false,
+      quiet:       false,
+      scroll:      false,
+      scrollSensitivity: 20,
+      scrollSpeed: 15,
+      format:      this.SERIALIZE_RULE,
+
+      // these take arrays of elements or ids and can be
+      // used for better initialization performance
+      elements:    false,
+      handles:     false,
+
+      onChange:    Prototype.emptyFunction,
+      onUpdate:    Prototype.emptyFunction
+    }, arguments[1] || { });
+
+    // clear any old sortable with same element
+    this.destroy(element);
+
+    // build options for the draggables
+    var options_for_draggable = {
+      revert:      true,
+      quiet:       options.quiet,
+      scroll:      options.scroll,
+      scrollSpeed: options.scrollSpeed,
+      scrollSensitivity: options.scrollSensitivity,
+      delay:       options.delay,
+      ghosting:    options.ghosting,
+      constraint:  options.constraint,
+      handle:      options.handle };
+
+    if(options.starteffect)
+      options_for_draggable.starteffect = options.starteffect;
+
+    if(options.reverteffect)
+      options_for_draggable.reverteffect = options.reverteffect;
+    else
+      if(options.ghosting) options_for_draggable.reverteffect = function(element) {
+        element.style.top  = 0;
+        element.style.left = 0;
+      };
+
+    if(options.endeffect)
+      options_for_draggable.endeffect = options.endeffect;
+
+    if(options.zindex)
+      options_for_draggable.zindex = options.zindex;
+
+    // build options for the droppables
+    var options_for_droppable = {
+      overlap:     options.overlap,
+      containment: options.containment,
+      tree:        options.tree,
+      hoverclass:  options.hoverclass,
+      onHover:     Sortable.onHover
+    };
+
+    var options_for_tree = {
+      onHover:      Sortable.onEmptyHover,
+      overlap:      options.overlap,
+      containment:  options.containment,
+      hoverclass:   options.hoverclass
+    };
+
+    // fix for gecko engine
+    Element.cleanWhitespace(element);
+
+    options.draggables = [];
+    options.droppables = [];
+
+    // drop on empty handling
+    if(options.dropOnEmpty || options.tree) {
+      Droppables.add(element, options_for_tree);
+      options.droppables.push(element);
+    }
+
+    (options.elements || this.findElements(element, options) || []).each( function(e,i) {
+      var handle = options.handles ? $(options.handles[i]) :
+        (options.handle ? $(e).select('.' + options.handle)[0] : e);
+      options.draggables.push(
+        new Draggable(e, Object.extend(options_for_draggable, { handle: handle })));
+      Droppables.add(e, options_for_droppable);
+      if(options.tree) e.treeNode = element;
+      options.droppables.push(e);
+    });
+
+    if(options.tree) {
+      (Sortable.findTreeElements(element, options) || []).each( function(e) {
+        Droppables.add(e, options_for_tree);
+        e.treeNode = element;
+        options.droppables.push(e);
+      });
+    }
+
+    // keep reference
+    this.sortables[element.identify()] = options;
+
+    // for onupdate
+    Draggables.addObserver(new SortableObserver(element, options.onUpdate));
+
+  },
+
+  // return all suitable-for-sortable elements in a guaranteed order
+  findElements: function(element, options) {
+    return Element.findChildren(
+      element, options.only, options.tree ? true : false, options.tag);
+  },
+
+  findTreeElements: function(element, options) {
+    return Element.findChildren(
+      element, options.only, options.tree ? true : false, options.treeTag);
+  },
+
+  onHover: function(element, dropon, overlap) {
+    if(Element.isParent(dropon, element)) return;
+
+    if(overlap > .33 && overlap < .66 && Sortable.options(dropon).tree) {
+      return;
+    } else if(overlap>0.5) {
+      Sortable.mark(dropon, 'before');
+      if(dropon.previousSibling != element) {
+        var oldParentNode = element.parentNode;
+        element.style.visibility = "hidden"; // fix gecko rendering
+        dropon.parentNode.insertBefore(element, dropon);
+        if(dropon.parentNode!=oldParentNode)
+          Sortable.options(oldParentNode).onChange(element);
+        Sortable.options(dropon.parentNode).onChange(element);
+      }
+    } else {
+      Sortable.mark(dropon, 'after');
+      var nextElement = dropon.nextSibling || null;
+      if(nextElement != element) {
+        var oldParentNode = element.parentNode;
+        element.style.visibility = "hidden"; // fix gecko rendering
+        dropon.parentNode.insertBefore(element, nextElement);
+        if(dropon.parentNode!=oldParentNode)
+          Sortable.options(oldParentNode).onChange(element);
+        Sortable.options(dropon.parentNode).onChange(element);
+      }
+    }
+  },
+
+  onEmptyHover: function(element, dropon, overlap) {
+    var oldParentNode = element.parentNode;
+    var droponOptions = Sortable.options(dropon);
+
+    if(!Element.isParent(dropon, element)) {
+      var index;
+
+      var children = Sortable.findElements(dropon, {tag: droponOptions.tag, only: droponOptions.only});
+      var child = null;
+
+      if(children) {
+        var offset = Element.offsetSize(dropon, droponOptions.overlap) * (1.0 - overlap);
+
+        for (index = 0; index < children.length; index += 1) {
+          if (offset - Element.offsetSize (children[index], droponOptions.overlap) >= 0) {
+            offset -= Element.offsetSize (children[index], droponOptions.overlap);
+          } else if (offset - (Element.offsetSize (children[index], droponOptions.overlap) / 2) >= 0) {
+            child = index + 1 < children.length ? children[index + 1] : null;
+            break;
+          } else {
+            child = children[index];
+            break;
+          }
+        }
+      }
+
+      dropon.insertBefore(element, child);
+
+      Sortable.options(oldParentNode).onChange(element);
+      droponOptions.onChange(element);
+    }
+  },
+
+  unmark: function() {
+    if(Sortable._marker) Sortable._marker.hide();
+  },
+
+  mark: function(dropon, position) {
+    // mark on ghosting only
+    var sortable = Sortable.options(dropon.parentNode);
+    if(sortable && !sortable.ghosting) return;
+
+    if(!Sortable._marker) {
+      Sortable._marker =
+        ($('dropmarker') || Element.extend(document.createElement('DIV'))).
+          hide().addClassName('dropmarker').setStyle({position:'absolute'});
+      document.getElementsByTagName("body").item(0).appendChild(Sortable._marker);
+    }
+    var offsets = dropon.cumulativeOffset();
+    Sortable._marker.setStyle({left: offsets[0]+'px', top: offsets[1] + 'px'});
+
+    if(position=='after')
+      if(sortable.overlap == 'horizontal')
+        Sortable._marker.setStyle({left: (offsets[0]+dropon.clientWidth) + 'px'});
+      else
+        Sortable._marker.setStyle({top: (offsets[1]+dropon.clientHeight) + 'px'});
+
+    Sortable._marker.show();
+  },
+
+  _tree: function(element, options, parent) {
+    var children = Sortable.findElements(element, options) || [];
+
+    for (var i = 0; i < children.length; ++i) {
+      var match = children[i].id.match(options.format);
+
+      if (!match) continue;
+
+      var child = {
+        id: encodeURIComponent(match ? match[1] : null),
+        element: element,
+        parent: parent,
+        children: [],
+        position: parent.children.length,
+        container: $(children[i]).down(options.treeTag)
+      };
+
+      /* Get the element containing the children and recurse over it */
+      if (child.container)
+        this._tree(child.container, options, child);
+
+      parent.children.push (child);
+    }
+
+    return parent;
+  },
+
+  tree: function(element) {
+    element = $(element);
+    var sortableOptions = this.options(element);
+    var options = Object.extend({
+      tag: sortableOptions.tag,
+      treeTag: sortableOptions.treeTag,
+      only: sortableOptions.only,
+      name: element.id,
+      format: sortableOptions.format
+    }, arguments[1] || { });
+
+    var root = {
+      id: null,
+      parent: null,
+      children: [],
+      container: element,
+      position: 0
+    };
+
+    return Sortable._tree(element, options, root);
+  },
+
+  /* Construct a [i] index for a particular node */
+  _constructIndex: function(node) {
+    var index = '';
+    do {
+      if (node.id) index = '[' + node.position + ']' + index;
+    } while ((node = node.parent) != null);
+    return index;
+  },
+
+  sequence: function(element) {
+    element = $(element);
+    var options = Object.extend(this.options(element), arguments[1] || { });
+
+    return $(this.findElements(element, options) || []).map( function(item) {
+      return item.id.match(options.format) ? item.id.match(options.format)[1] : '';
+    });
+  },
+
+  setSequence: function(element, new_sequence) {
+    element = $(element);
+    var options = Object.extend(this.options(element), arguments[2] || { });
+
+    var nodeMap = { };
+    this.findElements(element, options).each( function(n) {
+        if (n.id.match(options.format))
+            nodeMap[n.id.match(options.format)[1]] = [n, n.parentNode];
+        n.parentNode.removeChild(n);
+    });
+
+    new_sequence.each(function(ident) {
+      var n = nodeMap[ident];
+      if (n) {
+        n[1].appendChild(n[0]);
+        delete nodeMap[ident];
+      }
+    });
+  },
+
+  serialize: function(element) {
+    element = $(element);
+    var options = Object.extend(Sortable.options(element), arguments[1] || { });
+    var name = encodeURIComponent(
+      (arguments[1] && arguments[1].name) ? arguments[1].name : element.id);
+
+    if (options.tree) {
+      return Sortable.tree(element, arguments[1]).children.map( function (item) {
+        return [name + Sortable._constructIndex(item) + "[id]=" +
+                encodeURIComponent(item.id)].concat(item.children.map(arguments.callee));
+      }).flatten().join('&');
+    } else {
+      return Sortable.sequence(element, arguments[1]).map( function(item) {
+        return name + "[]=" + encodeURIComponent(item);
+      }).join('&');
+    }
+  }
+};
+
+// Returns true if child is contained within element
+Element.isParent = function(child, element) {
+  if (!child.parentNode || child == element) return false;
+  if (child.parentNode == element) return true;
+  return Element.isParent(child.parentNode, element);
+};
+
+Element.findChildren = function(element, only, recursive, tagName) {
+  if(!element.hasChildNodes()) return null;
+  tagName = tagName.toUpperCase();
+  if(only) only = [only].flatten();
+  var elements = [];
+  $A(element.childNodes).each( function(e) {
+    if(e.tagName && e.tagName.toUpperCase()==tagName &&
+      (!only || (Element.classNames(e).detect(function(v) { return only.include(v) }))))
+        elements.push(e);
+    if(recursive) {
+      var grandchildren = Element.findChildren(e, only, recursive, tagName);
+      if(grandchildren) elements.push(grandchildren);
+    }
+  });
+
+  return (elements.length>0 ? elements.flatten() : []);
+};
+
+Element.offsetSize = function (element, type) {
+  return element['offset' + ((type=='vertical' || type=='height') ? 'Height' : 'Width')];
+};
\ No newline at end of file