// script.aculo.us dragdrop.js v1.7.1_beta3, Fri May 25 17:19:41 +0200 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();

		// PBT, uncommented
		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);
		}

		// PBT, uncommented
		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 = [];

		// PBT: 
		this.optionsDrag = options_for_draggable;
		this.optionsDrop = options_for_droppable;

		// 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;
		
		// PBT: uncomment if needed
		// element.style.height = "20px";

		// for onupdate
		Draggables.addObserver(new SortableObserver(element, options.onUpdate));

	},

	// PBT:
	optionsDrag: null,
	optionsDrop: null,

	// 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')];
}

// [AtlasScript]

if (window.Sys)
	Sys.Application.notifyScriptLoaded();

// [/AtlasScript]