Dynamically changed grid page size

[Radek]

Hi, I'm workinkg on Kendo grid and I'd like to dynamically change grid page size.
There is a problem when I change pageSize property by the function from

$("#somegrid").data('kendoGrid').dataSource.pageSize(10);

There are some options in my grid pager dropdown like: 5, 10, 15, 20, but when i use this function, selected value in that dropdown doesn't change. How can I change it's selected value? I'm always setting value that exists in that dropdown.