/**

  * 如果列表同时存在横向滚动条和竖向滚动条，当竖向滚动条滚动到底部时

  * 点击横向滚动条，滚动条会自动滚动到顶部

  * 6.2.1 bug修复

  */

 Ext.define('override.grid.NavigationModel', {

     override: 'Ext.grid.NavigationModel',

     //当列表被点击时

     onContainerMouseDown: function (view, mousedownEvent) {

         var me = this,

         context = new Ext.grid.CellContext(view),

         lastFocused,

         position;

         //执行Ext.grid.NavigationModel父类的同名方法

         //执行此方法后如果点击的是滚动条view.lastFocused的值会变为scrollbar

         //可以由此判断点击的是滚动条还是列表内容

         //这样就能解决这个bug

         me.callSuper([view, mousedownEvent]);

         lastFocused = view.lastFocused;

         position = (view.actionableMode && view.actionPosition) || lastFocused;

         //判断点击的元素是否是滚动条，如果是则不做任何操作

         if (!position || lastFocused === 'scrollbar') {

             return;

         }

         context.setPosition(position.record, position.column);

         mousedownEvent.position = context;

         me.attachClosestCell(mousedownEvent);

         // If we are not already on that position, set position there.

         if (!me.position.isEqual(context)) {

             me.setPosition(context, null, mousedownEvent);

         }

     }

 });