    /**
     * @class Ext.grid.plugin.HeaderReorderer
     * @extends Ext.util.Observable
     * @private
     */
    Ext.define('Ext.grid.plugin.HeaderReorderer', {
        extend: 'Ext.util.Observable',
        requires: ['Ext.grid.header.DragZone', 'Ext.grid.header.DropZone'],
        alias: 'plugin.gridheaderreorderer',

        init: function(headerCt) {
            this.headerCt = headerCt;
            headerCt.on('render', this.onHeaderCtRender, this);
        },

        /**
         * @private
         * AbstractComponent calls destroy on all its plugins at destroy time.
         */
        destroy: function() {
            Ext.destroy(this.dragZone, this.dropZone);
        },

        onHeaderCtRender: function() {
            this.dragZone = Ext.create('Ext.grid.header.DragZone', this.headerCt);
            this.dropZone = Ext.create('Ext.grid.header.DropZone', this.headerCt);
            if (this.disabled) {
                this.dragZone.disable();
            }
        },

        enable: function() {
            this.disabled = false;
            if (this.dragZone) {
                this.dragZone.enable();
            }
        },

        disable: function() {
            this.disabled = true;
            if (this.dragZone) {
                this.dragZone.disable();
            }
        }
    });