#sortable {
	list-style: none;
	padding: 0px;
	height: 396px;
	display: block; 
	position: relative;
} 

#sortable .item {
	width: 81px;
	height: 84px;
	float: left;
}

jQuery demo.js

jQuery(function($) {
    window.SelectionModel = function(selector) {
        this.mostRecentSelection = null;
        this.selector = selector;
        var that = this;
        that.clearSelection();

        $(selector).live('mousedown', function(event) {
        	alert($('#selector'));
            that.handleSelectionEvent($(this), event);                
            return false;
        });
    }
    
    SelectionModel.prototype = {
        handleSelectionEvent: function(clicked, event) {
            var ctrl = event.ctrlKey || event.metaKey; // Detect metaKey for OSX users
            
            if(event.shiftKey) {
                var selectable = $(this.selector)
                var previousSelectionIndex = selectable.index(this.mostRecentSelection || clicked);
                var currentSelectionIndex = selectable.index(clicked);
                var rangeMax = Math.max(previousSelectionIndex, currentSelectionIndex);
                var rangeMin = Math.min(previousSelectionIndex, currentSelectionIndex);
                            
                for (; rangeMin <= rangeMax; rangeMin++) {
                    if($(this.currentSelection).index(selectable[rangeMin]) != -1) continue;
                    $(selectable[rangeMin]).addClass('activated');
                    this.addToSelection(selectable[rangeMin]);
                }
            }
            else if(clicked.is('.activated')) {
                if(ctrl) {
                    this.removeFromSelection(clicked[0]);     
                    clicked.toggleClass('activated');                
                }
            }
            else {
                if(ctrl) {
                    this.addToSelection(clicked[0]);     
                }
                else {
                    this.clearSelection();
                    this.addToSelection(clicked[0])
                }
                clicked.toggleClass('activated');                
            }        
            this.mostRecentSelection = clicked;
        }
        ,addToSelection: function(element) {
            this.currentSelection.push(element);
        },
        removeFromSelection: function(element) {
            var newSelection = [];
            $(this.currentSelection).each(function(which, item) {
                if(item != element) newSelection.push(item); 
            });
            this.currentSelection = $(newSelection);
        },
        clearSelection: function() {
            $(this.selector).removeClass('activated');
            this.currentSelection = [];
        }
    };