javascript easyui treegrid點擊行即可伸縮

treegrid點擊小箭頭纔可伸縮，不方便；

    function drawtreegrid(data,id,filter,sort){
        var col=[];
        var arrdata=typeof data.rows!=='object' ? JSON.parse(data.rows):data.rows;
        for(var index in arrdata[1]){
            if(index!=='id' && index!=='_parentId'){
            col.push({'field':index,'title':index,'width':100,'sortable':sort});
            }
        };
        $('#'+id).treegrid({
            data:data,
            //singleSelect: true,
            rownumbers: true,
            //showFooter: false,
            //fitColumns: true,
            //remoteSort:false,
            idField: 'id',
            treeField: col[0]['field'],
            columns:[col],
            onClickCell:function(a,b){
                if(a==col[0]['field']){
                    if(b.state=='open'){
                    $('#'+id).treegrid('collapse',b.id);
                    }
                    else {
                    $('#'+id).treegrid('expand',b.id) ;
                    }
                }
                else{
                    return;
                }
                }
        });
      

    };