Drag.Group = new Class({

    Implements : [Options],

    options : {
        'active' : true,
        'store' : 'drag-group-item',
        'filter' : $lambda(true),
        'drag' : {}
    },
    
    elements : [],

    initialize : function(options){
        this.setOptions(options);
    },

    add : function(el,options){
        var drag = new Drag.Group.Item(el, this, $merge(this.options.drag,options))
        el.store(this.options.store, drag );
        this.elements.push(el);
        return drag;
    },
    
    start : function(el,event){
        if(!this.options.active || !this.options.filter(el)) 
            el.retrieve(this.options.store).start(event,true);
        else {
            this.elements.filter(this.options.filter).each(function(match){
                match.retrieve(this.options.store).start(event,true);
            },this);
        }
    }
});

Drag.Group.Item = new Class({

    Extends : Drag.Move,
    
    initialize : function(el,group,options){
        this.group = group;
        this.parent(el,options);
    },
    
    start : function(event,alerted){
        if(alerted) this.parent(event);
        else this.group.start(this.element,event);
    }

});