    /**
     * @class Ext.util.ComponentDragger
     * @extends Ext.dd.DragTracker
     * <p>A subclass of Ext.dd.DragTracker which handles dragging any Component.</p>
     * <p>This is configured with a Component to be made draggable, and a config object for the
     * {@link Ext.dd.DragTracker} class.</p>
     * <p>A {@link #} delegate may be provided which may be either the element to use as the mousedown target
     * or a {@link Ext.DomQuery} selector to activate multiple mousedown targets.</p>
     * @constructor Create a new ComponentTracker
     * @param {object} comp The Component to provide dragging for.
     * @param {object} config The config object
     */
    Ext.define('Ext.util.ComponentDragger', {

        /**
         * @cfg {Boolean} constrain
         * Specify as <code>true</code> to constrain the Component to within the bounds of the {@link #constrainTo} region.
         */

        /**
         * @cfg {String/Element} delegate
         * Optional. <p>A {@link Ext.DomQuery DomQuery} selector which identifies child elements within the Component's encapsulating
         * Element which are the drag handles. This limits dragging to only begin when the matching elements are mousedowned.</p>
         * <p>This may also be a specific child element within the Component's encapsulating element to use as the drag handle.</p>
         */

        /**
         * @cfg {Boolean} constrainDelegate
         * Specify as <code>true</code> to constrain the drag handles within the {@link constrainTo} region.
         */

        extend: 'Ext.dd.DragTracker',

        autoStart: 500,

        constructor: function(comp, config) {
            this.comp = comp;
            this.initialConstrainTo = config.constrainTo;
            this.callParent([ config ]);
        },

        onStart: function(e) {
            var me = this,
                comp = me.comp;

            // Cache the start [X, Y] array
            this.startPosition = comp.getPosition();

            // If client Component has a ghost method to show a lightweight version of itself
            // then use that as a drag proxy unless configured to liveDrag.
            if (comp.ghost && !comp.liveDrag) {
                 me.proxy = comp.ghost();
                 me.dragTarget = me.proxy.header.el;
            }

            // Set the constrainTo Region before we start dragging.
            if (me.constrain || me.constrainDelegate) {
                me.constrainTo = me.calculateConstrainRegion();
            }
        },

        calculateConstrainRegion: function() {
            var me = this,
                comp = me.comp,
                c = me.initialConstrainTo,
                delegateRegion,
                elRegion,
                shadowSize = comp.el.shadow ? comp.el.shadow.offset : 0;

            // The configured constrainTo might be a Region or an element
            if (!(c instanceof Ext.util.Region)) {
                c =  Ext.fly(c).getViewRegion();
            }

            // Reduce the constrain region to allow for shadow
            if (shadowSize) {
                c.adjust(0, -shadowSize, -shadowSize, shadowSize);
            }

            // If they only want to constrain the *delegate* to within the constrain region,
            // adjust the region to be larger based on the insets of the delegate from the outer
            // edges of the Component.
            if (!me.constrainDelegate) {
                delegateRegion = Ext.fly(me.dragTarget).getRegion();
                elRegion = me.proxy ? me.proxy.el.getRegion() : comp.el.getRegion();

                c.adjust(
                    delegateRegion.top - elRegion.top,
                    delegateRegion.right - elRegion.right,
                    delegateRegion.bottom - elRegion.bottom,
                    delegateRegion.left - elRegion.left
                );
            }
            return c;
        },

        // Move either the ghost Component or the target Component to its new position on drag
        onDrag: function(e) {
            var me = this,
                comp = (me.proxy && !me.comp.liveDrag) ? me.proxy : me.comp,
                offset = me.getOffset(me.constrain || me.constrainDelegate ? 'dragTarget' : null);

            comp.setPosition.apply(comp, [me.startPosition[0] + offset[0], me.startPosition[1] + offset[1]]);
        },

        onEnd: function(e) {
            if (this.proxy && !this.comp.liveDrag) {
                this.comp.unghost();
            }
        }
    });