I have a Grid inside a StackPanel
when I click on an expand button
something very strange happens:
it looks like the scrolls are flashing:
appear and disappear .. appear and disappear .. appear and disappear
Grid panel with RowDefinition Height=Auto is measuring this content with Infinity. This is why the scroll viewer is not showing. You should modify your xaml and place RadGridView in a row that is with Fixed or Star height if you want scroll viewer and virtualization to work.