    /**
     * @class Ext.grid.Lockable
     * @private
     *
     * Lockable is a private mixin which injects lockable behavior into any
     * TablePanel subclass such as GridPanel or TreePanel. TablePanel will
     * automatically inject the Ext.grid.Lockable mixin in when one of the
     * these conditions are met:
     * - The TablePanel has the lockable configuration set to true
     * - One of the columns in the TablePanel has locked set to true/false
     *
     * Each TablePanel subclass *must* register an alias. It should have an array
     * of configurations to copy to the 2 separate tablepanel's that will be generated
     * to note what configurations should be copied. These are named normalCfgCopy and
     * lockedCfgCopy respectively.
     *
     * Columns which are locked must specify a fixed width. They do *NOT* support a
     * flex width.
     *
     * Configurations which are specified in this class will be available on any grid or
     * tree which is using the lockable functionality.
     */
    Ext.define('Ext.grid.Lockable', {

        requires: ['Ext.grid.LockingView'],

        /**
         * @cfg {Boolean} syncRowHeight Synchronize rowHeight between the normal and
         * locked grid view. This is turned on by default. If your grid is guaranteed
         * to have rows of all the same height, you should set this to false to
         * optimize performance.
         */
        syncRowHeight: true,

        /**
         * @cfg {String} subGridXType The xtype of the subgrid to specify. If this is
         * not specified lockable will determine the subgrid xtype to create by the
         * following rule. Use the superclasses xtype if the superclass is NOT
         * tablepanel, otherwise use the xtype itself.
         */

        /**
         * @cfg {Object} lockedViewConfig A view configuration to be applied to the
         * locked side of the grid. Any conflicting configurations between lockedViewConfig
         * and viewConfig will be overwritten by the lockedViewConfig.
         */

        /**
         * @cfg {Object} normalViewConfig A view configuration to be applied to the
         * normal/unlocked side of the grid. Any conflicting configurations between normalViewConfig
         * and viewConfig will be overwritten by the normalViewConfig.
         */

        // private variable to track whether or not the spacer is hidden/visible
        spacerHidden: true,

        // i8n text
        unlockText: 'Unlock',
        lockText: 'Lock',

        determineXTypeToCreate: function() {
            var me = this,
                typeToCreate;

            if (me.subGridXType) {
                typeToCreate = me.subGridXType;
            } else {
                var xtypes     = this.getXTypes().split('/'),
                    xtypesLn   = xtypes.length,
                    xtype      = xtypes[xtypesLn - 1],
                    superxtype = xtypes[xtypesLn - 2];

                if (superxtype !== 'tablepanel') {
                    typeToCreate = superxtype;
                } else {
                    typeToCreate = xtype;
                }
            }

            return typeToCreate;
        },

        // injectLockable will be invoked before initComponent's parent class implementation
        // is called, so throughout this method this. are configurations
        injectLockable: function() {
            // ensure lockable is set to true in the TablePanel
            this.lockable = true;
            // Instruct the TablePanel it already has a view and not to create one.
            // We are going to aggregate 2 copies of whatever TablePanel we are using
            this.hasView = true;

            var me = this,
                // xtype of this class, 'treepanel' or 'gridpanel'
                // (Note: this makes it a requirement that any subclass that wants to use lockable functionality needs to register an
                // alias.)
                xtype = me.determineXTypeToCreate(),
                // share the selection model
                selModel = me.getSelectionModel(),
                lockedGrid = {
                    xtype: xtype,
                    // Lockable does NOT support animations for Tree
                    enableAnimations: false,
                    scroll: false,
                    scrollerOwner: false,
                    selModel: selModel,
                    border: false,
                    cls: Ext.baseCSSPrefix + 'grid-inner-locked'
                },
                normalGrid = {
                    xtype: xtype,
                    enableAnimations: false,
                    scrollerOwner: false,
                    selModel: selModel,
                    border: false
                },
                i = 0,
                columns,
                lockedHeaderCt,
                normalHeaderCt;

            me.addCls(Ext.baseCSSPrefix + 'grid-locked');

            // copy appropriate configurations to the respective
            // aggregated tablepanel instances and then delete them
            // from the master tablepanel.
            Ext.copyTo(normalGrid, me, me.normalCfgCopy);
            Ext.copyTo(lockedGrid, me, me.lockedCfgCopy);
            for (; i < me.normalCfgCopy.length; i++) {
                delete me[me.normalCfgCopy[i]];
            }
            for (i = 0; i < me.lockedCfgCopy.length; i++) {
                delete me[me.lockedCfgCopy[i]];
            }

            me.lockedHeights = [];
            me.normalHeights = [];

            columns = me.processColumns(me.columns);

            lockedGrid.width = columns.lockedWidth;
            lockedGrid.columns = columns.locked;
            normalGrid.columns = columns.normal;

            me.store = Ext.StoreManager.lookup(me.store);
            lockedGrid.store = me.store;
            normalGrid.store = me.store;

            // normal grid should flex the rest of the width
            normalGrid.flex = 1;
            lockedGrid.viewConfig = me.lockedViewConfig || {};
            lockedGrid.viewConfig.loadingUseMsg = false;
            normalGrid.viewConfig = me.normalViewConfig || {};

            Ext.applyIf(lockedGrid.viewConfig, me.viewConfig);
            Ext.applyIf(normalGrid.viewConfig, me.viewConfig);

            me.normalGrid = Ext.ComponentManager.create(normalGrid);
            me.lockedGrid = Ext.ComponentManager.create(lockedGrid);

            me.view = Ext.create('Ext.grid.LockingView', {
                locked: me.lockedGrid,
                normal: me.normalGrid,
                panel: me
            });

            if (me.syncRowHeight) {
                me.lockedGrid.getView().on({
                    refresh: me.onLockedGridAfterRefresh,
                    itemupdate: me.onLockedGridAfterUpdate,
                    scope: me
                });

                me.normalGrid.getView().on({
                    refresh: me.onNormalGridAfterRefresh,
                    itemupdate: me.onNormalGridAfterUpdate,
                    scope: me
                });
            }

            lockedHeaderCt = me.lockedGrid.headerCt;
            normalHeaderCt = me.normalGrid.headerCt;

            lockedHeaderCt.lockedCt = true;
            lockedHeaderCt.lockableInjected = true;
            normalHeaderCt.lockableInjected = true;

            lockedHeaderCt.on({
                columnshow: me.onLockedHeaderShow,
                columnhide: me.onLockedHeaderHide,
                columnmove: me.onLockedHeaderMove,
                sortchange: me.onLockedHeaderSortChange,
                columnresize: me.onLockedHeaderResize,
                scope: me
            });

            normalHeaderCt.on({
                columnmove: me.onNormalHeaderMove,
                sortchange: me.onNormalHeaderSortChange,
                scope: me
            });

            me.normalGrid.on({
                scrollershow: me.onScrollerShow,
                scrollerhide: me.onScrollerHide,
                scope: me
            });

            me.lockedGrid.on('afterlayout', me.onLockedGridAfterLayout, me, {single: true});

            me.modifyHeaderCt();
            me.items = [me.lockedGrid, me.normalGrid];

            me.layout = {
                type: 'hbox',
                align: 'stretch'
            };
        },

        processColumns: function(columns){
            // split apart normal and lockedWidths
            var i = 0,
                len = columns.length,
                lockedWidth = 0,
                lockedHeaders = [],
                normalHeaders = [],
                column;

            for (; i < len; ++i) {
                column = columns[i];
                // mark the column as processed so that the locked attribute does not
                // trigger trying to aggregate the columns again.
                column.processed = true;
                if (column.locked) {
                    // <debug>
                    if (column.flex) {
                        Ext.Error.raise("Columns which are locked do NOT support a flex width. You must set a width on the " + columns[i].text + "column.");
                    }
                    // </debug>
                    lockedWidth += column.width;
                    lockedHeaders.push(column);
                } else {
                    normalHeaders.push(column);
                }
            }
            return {
                lockedWidth: lockedWidth,
                locked: lockedHeaders,
                normal: normalHeaders
            };
        },

        // create a new spacer after the table is refreshed
        onLockedGridAfterLayout: function() {
            var me         = this,
                lockedView = me.lockedGrid.getView();
            lockedView.on({
                refresh: me.createSpacer,
                beforerefresh: me.destroySpacer,
                scope: me
            });
        },

        // trigger a pseudo refresh on the normal side
        onLockedHeaderMove: function() {
            if (this.syncRowHeight) {
                this.onNormalGridAfterRefresh();
            }
        },

        // trigger a pseudo refresh on the locked side
        onNormalHeaderMove: function() {
            if (this.syncRowHeight) {
                this.onLockedGridAfterRefresh();
            }
        },

        // create a spacer in lockedsection and store a reference
        // TODO: Should destroy before refreshing content
        createSpacer: function() {
            var me   = this,
                // This affects scrolling all the way to the bottom of a locked grid
                // additional test, sort a column and make sure it synchronizes
                w    = Ext.getScrollBarWidth() + (Ext.isIE ? 2 : 0),
                view = me.lockedGrid.getView(),
                el   = view.el;

            me.spacerEl = Ext.core.DomHelper.append(el, {
                cls: me.spacerHidden ? (Ext.baseCSSPrefix + 'hidden') : '',
                style: 'height: ' + w + 'px;'
            }, true);
        },

        destroySpacer: function() {
            var me = this;
            if (me.spacerEl) {
                me.spacerEl.destroy();
                delete me.spacerEl;
            }
        },

        // cache the heights of all locked rows and sync rowheights
        onLockedGridAfterRefresh: function() {
            var me     = this,
                view   = me.lockedGrid.getView(),
                el     = view.el,
                rowEls = el.query(view.getItemSelector()),
                ln     = rowEls.length,
                i = 0;

            // reset heights each time.
            me.lockedHeights = [];

            for (; i < ln; i++) {
                me.lockedHeights[i] = rowEls[i].clientHeight;
            }
            me.syncRowHeights();
        },

        // cache the heights of all normal rows and sync rowheights
        onNormalGridAfterRefresh: function() {
            var me     = this,
                view   = me.normalGrid.getView(),
                el     = view.el,
                rowEls = el.query(view.getItemSelector()),
                ln     = rowEls.length,
                i = 0;

            // reset heights each time.
            me.normalHeights = [];

            for (; i < ln; i++) {
                me.normalHeights[i] = rowEls[i].clientHeight;
            }
            me.syncRowHeights();
        },

        // rows can get bigger/smaller
        onLockedGridAfterUpdate: function(record, index, node) {
            this.lockedHeights[index] = node.clientHeight;
            this.syncRowHeights();
        },

        // rows can get bigger/smaller
        onNormalGridAfterUpdate: function(record, index, node) {
            this.normalHeights[index] = node.clientHeight;
            this.syncRowHeights();
        },

        // match the rowheights to the biggest rowheight on either
        // side
        syncRowHeights: function() {
            var me = this,
                lockedHeights = me.lockedHeights,
                normalHeights = me.normalHeights,
                calcHeights   = [],
                ln = lockedHeights.length,
                i  = 0,
                lockedView, normalView,
                lockedRowEls, normalRowEls,
                vertScroller = me.getVerticalScroller(),
                scrollTop;

            // ensure there are an equal num of locked and normal
            // rows before synchronization
            if (lockedHeights.length && normalHeights.length) {
                lockedView = me.lockedGrid.getView();
                normalView = me.normalGrid.getView();
                lockedRowEls = lockedView.el.query(lockedView.getItemSelector());
                normalRowEls = normalView.el.query(normalView.getItemSelector());

                // loop thru all of the heights and sync to the other side
                for (; i < ln; i++) {
                    // ensure both are numbers
                    if (!isNaN(lockedHeights[i]) && !isNaN(normalHeights[i])) {
                        if (lockedHeights[i] > normalHeights[i]) {
                            Ext.fly(normalRowEls[i]).setHeight(lockedHeights[i]);
                        } else if (lockedHeights[i] < normalHeights[i]) {
                            Ext.fly(lockedRowEls[i]).setHeight(normalHeights[i]);
                        }
                    }
                }

                // invalidate the scroller and sync the scrollers
                me.normalGrid.invalidateScroller();

                // synchronize the view with the scroller, if we have a virtualScrollTop
                // then the user is using a PagingScroller
                if (vertScroller && vertScroller.setViewScrollTop) {
                    vertScroller.setViewScrollTop(me.virtualScrollTop);
                } else {
                    // We don't use setScrollTop here because if the scrollTop is
                    // set to the exact same value some browsers won't fire the scroll
                    // event. Instead, we directly set the scrollTop.
                    scrollTop = normalView.el.dom.scrollTop;
                    normalView.el.dom.scrollTop = scrollTop;
                    lockedView.el.dom.scrollTop = scrollTop;
                }

                // reset the heights
                me.lockedHeights = [];
                me.normalHeights = [];
            }
        },

        // track when scroller is shown
        onScrollerShow: function(scroller, direction) {
            if (direction === 'horizontal') {
                this.spacerHidden = false;
                this.spacerEl.removeCls(Ext.baseCSSPrefix + 'hidden');
            }
        },

        // track when scroller is hidden
        onScrollerHide: function(scroller, direction) {
            if (direction === 'horizontal') {
                this.spacerHidden = true;
                this.spacerEl.addCls(Ext.baseCSSPrefix + 'hidden');
            }
        },

        // inject Lock and Unlock text
        modifyHeaderCt: function() {
            var me = this;
            me.lockedGrid.headerCt.getMenuItems = me.getMenuItems(true);
            me.normalGrid.headerCt.getMenuItems = me.getMenuItems(false);
        },

        onUnlockMenuClick: function() {
            this.unlock();
        },

        onLockMenuClick: function() {
            this.lock();
        },

        getMenuItems: function(locked) {
            var me            = this,
                unlockText    = me.unlockText,
                lockText      = me.lockText,
                // TODO: Refactor to use Ext.baseCSSPrefix
                unlockCls     = 'xg-hmenu-unlock',
                lockCls       = 'xg-hmenu-lock',
                unlockHandler = Ext.Function.bind(me.onUnlockMenuClick, me),
                lockHandler   = Ext.Function.bind(me.onLockMenuClick, me);

            // runs in the scope of headerCt
            return function() {
                var o = Ext.grid.header.Container.prototype.getMenuItems.call(this);
                o.push('-',{
                    cls: unlockCls,
                    text: unlockText,
                    handler: unlockHandler,
                    disabled: !locked
                });
                o.push({
                    cls: lockCls,
                    text: lockText,
                    handler: lockHandler,
                    disabled: locked
                });
                return o;
            };
        },

        // going from unlocked section to locked
        /**
         * Locks the activeHeader as determined by which menu is open OR a header
         * as specified.
         * @param {Ext.grid.column.Column} header (Optional) Header to unlock from the locked section. Defaults to the header which has the menu open currently.
         * @param {Number} toIdx (Optional) The index to move the unlocked header to. Defaults to appending as the last item.
         * @private
         */
        lock: function(activeHd, toIdx) {
            var me         = this,
                normalGrid = me.normalGrid,
                lockedGrid = me.lockedGrid,
                normalHCt  = normalGrid.headerCt,
                lockedHCt  = lockedGrid.headerCt;

            activeHd = activeHd || normalHCt.getMenu().activeHeader;

            // if column was previously flexed, get/set current width
            // and remove the flex
            if (activeHd.flex) {
                activeHd.width = activeHd.getWidth();
                delete activeHd.flex;
            }

            normalHCt.remove(activeHd, false);
            lockedHCt.suspendLayout = true;
            if (Ext.isDefined(toIdx)) {
                lockedHCt.insert(toIdx, activeHd);
            } else {
                lockedHCt.add(activeHd);
            }
            lockedHCt.suspendLayout = false;
            me.syncLockedSection();
        },

        syncLockedSection: function() {
            var me = this;
            me.syncLockedWidth();
            me.lockedGrid.getView().refresh();
            me.normalGrid.getView().refresh();
        },

        // adjust the locked section to the width of its respective
        // headerCt
        syncLockedWidth: function() {
            var me = this,
                width = me.lockedGrid.headerCt.getFullWidth(true);
            me.lockedGrid.setWidth(width);
        },

        onLockedHeaderResize: function() {
            this.syncLockedWidth();
        },

        onLockedHeaderHide: function() {
            this.syncLockedWidth();
        },

        onLockedHeaderShow: function() {
            this.syncLockedWidth();
        },

        onLockedHeaderSortChange: function(headerCt, header, sortState) {
            if (sortState) {
                // no real header, and silence the event so we dont get into an
                // infinite loop
                this.normalGrid.headerCt.clearOtherSortStates(null, true);
            }
        },

        onNormalHeaderSortChange: function(headerCt, header, sortState) {
            if (sortState) {
                // no real header, and silence the event so we dont get into an
                // infinite loop
                this.lockedGrid.headerCt.clearOtherSortStates(null, true);
            }
        },

        // going from locked section to unlocked
        /**
         * Unlocks the activeHeader as determined by which menu is open OR a header
         * as specified.
         * @param {Ext.grid.column.Column} header (Optional) Header to unlock from the locked section. Defaults to the header which has the menu open currently.
         * @param {Number} toIdx (Optional) The index to move the unlocked header to. Defaults to 0.
         * @private
         */
        unlock: function(activeHd, toIdx) {
            var me         = this,
                normalGrid = me.normalGrid,
                lockedGrid = me.lockedGrid,
                normalHCt  = normalGrid.headerCt,
                lockedHCt  = lockedGrid.headerCt;

            if (!Ext.isDefined(toIdx)) {
                toIdx = 0;
            }
            activeHd = activeHd || lockedHCt.getMenu().activeHeader;

            lockedHCt.remove(activeHd, false);
            me.syncLockedWidth();
            me.lockedGrid.getView().refresh();
            normalHCt.insert(toIdx, activeHd);
            me.normalGrid.getView().refresh();
        },

        // we want to totally override the reconfigure behaviour here, since we're creating 2 sub-grids
        reconfigureLockable: function(store, columns) {
            var me = this,
                lockedGrid = me.lockedGrid,
                normalGrid = me.normalGrid;

            if (columns) {
                lockedGrid.headerCt.removeAll();
                normalGrid.headerCt.removeAll();

                columns = me.processColumns(columns);
                lockedGrid.setWidth(columns.lockedWidth);
                lockedGrid.headerCt.add(columns.locked);
                normalGrid.headerCt.add(columns.normal);
            }

            if (store) {
                store = Ext.data.StoreManager.lookup(store);
                me.store = store;
                lockedGrid.bindStore(store);
                normalGrid.bindStore(store);
            } else {
                lockedGrid.getView().refresh();
                normalGrid.getView().refresh();
            }
        }
    });