The Tor Browser / file revision

 // script.aculo.us dragdrop.js v1.7.1_beta2, Tue May 15 15:15:45 EDT 2007

 // Copyright (c) 2005-2007 Thomas Fuchs (http://script.aculo.us, http://mir.aculo.us)

 //           (c) 2005-2007 Sammi Williams (http://www.oriontransfer.co.nz, sammi@oriontransfer.co.nz)

 // 

 // 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(typeof Effect == 'undefined')

   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((typeof containment == 'object') && 

         (containment.constructor == Array)) {

         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 affected = [];

     if(this.last_active) this.deactivate(this.last_active);

     this.drops.each( function(drop) {

       if(Droppables.isAffected(point, element, drop))

         affected.push(drop);

     });

     if(affected.length>0) {

       drop = Droppables.findDeepestChild(affected);

       Position.within(drop.element, point[0], point[1]);

       if(drop.onHover)

         drop.onHover(element, drop.element, Position.overlap(drop.overlap, drop.element));

       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();

 Draggable._dragging    = {};

 Draggable.prototype = {

   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 = typeof element._opacity == 'number' ? 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] || typeof arguments[1].endeffect == 'undefined')

       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 && (typeof options.handle == 'string'))

       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.delta    = this.currentDelta();

     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(typeof Draggable._dragging[this.element] != 'undefined' &&

       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     = Position.cumulativeOffset(this.element);

       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.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);

       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);

         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) {

       Position.relativize(this.element);

       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 && typeof revert == 'function') 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 = Position.cumulativeOffset(this.element);

     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(typeof this.options.snap == 'function') {

         p = this.options.snap(p[0],p[1],this);

       } else {

       if(this.options.snap instanceof Array) {

         p = p.map( function(v, i) {

           return Math.round(v/this.options.snap[i])*this.options.snap[i] }.bind(this))

       } else {

         p = p.map( function(v) {

           return Math.round(v/this.options.snap)*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 };

   }

 }

 /*--------------------------------------------------------------------------*/

 var SortableObserver = Class.create();

 SortableObserver.prototype = {

   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){

     var s = Sortable.options(element);

     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).getElementsByClassName(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.id] = 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 = Position.cumulativeOffset(dropon);

     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')];

 }