Change in DropDown in MainLayout shall update Datagrid

I add a Dropdown List in the MainLayout and I have a page with a datagrid.
When I select an item in the dropdown list, it shall update the datagrid and show only rows which are assigned to the seletced item in the dropdown list
I think the problem is similar from svrebelo001
My page with the datagrid does not reload.
What I have to write in the MainLayout DropDown OnChange Event ?

You need to bind the DropDown to a global property and use this global property to filter the DataGrid.