为datagrid、treegrid增加右键表头菜单，用于显示或隐藏列，注意：冻结列不在此菜单中

 var createGridHeaderContextMenu = function(e, field) {
     e.preventDefault();
     var grid = $(this);/* grid本身 */
     var headerContextMenu = this.headerContextMenu;/* grid上的列头菜单对象 */
     if (!headerContextMenu) {
         var tmenu = $('<div style="width:100px;"></div>').appendTo('body');
         var fields = grid.datagrid('getColumnFields');
         console.log('id='+grid.attr('id'));
          storage=$.localStorage;if(!storage)storage=$.cookieStorage;
         var cols = storage.get(grid.attr('id')+'hiddenColumns');
         var init=true;
         if(cols){
             init=false;
         }
         for ( var i = 0; i < fields.length; i++) {
             var fildOption = grid.datagrid('getColumnOption', fields[i]);
             console.log(fields[i]+'='+fildOption.hidden);
             if (!fildOption.hidden||fildOption.hidden==false) {
                 $('<div iconCls="icon-ok" field="' + fields[i] + '"/>').html(fildOption.title).appendTo(tmenu);
             } else {
                 if(init==false){
                     for(var j=0;j<cols.length;j++){
                         if(cols[j].field==fields[i]&&cols[j].visible!=false){
                             //console.log(cols[j].field+'=='+cols[j].visible);
                             $('<div iconCls="icon-empty" field="' + fields[i] + '"/>').html(fildOption.title).appendTo(tmenu);
                         }
                     }
                 }
             }
         }
         headerContextMenu = this.headerContextMenu = tmenu.menu({
             onClick : function(item) {
                 var field = $(item.target).attr('field');
                 if (item.iconCls == 'icon-ok') {
                     grid.datagrid('hideColumn', field);
                     $(this).menu('setIcon', {
                         target : item.target,
                         iconCls : 'icon-empty'
                     });
                 } else if (item.iconCls == 'icon-empty') {
                     grid.datagrid('showColumn', field);
                     $(this).menu('setIcon', {
                         target : item.target,
                         iconCls : 'icon-ok'
                     });
                 }else{
                     //恢复表头

                 }
             }
         });
     }
     headerContextMenu.menu('show', {
         left : e.pageX,
         top : e.pageY
     });
 };

 //$.fn.datagrid.defaults.onHeaderContextMenu = createGridHeaderContextMenu;     //屏蔽掉dagagrid表头右键隐藏列的功能
 $.fn.treegrid.defaults.onHeaderContextMenu = createGridHeaderContextMenu;