Hi,

We investigated this scenario and we have chosen not to address this behavior.

The temporary appearance of the horizontal scrollbar can be observed when reducing the size of the container/window the RadGridView is placed in. This leads to it being measured with a size less than the one it is currently spanning, which in turn causes the horizontal scrollbar to be visible for a brief instant. There isn't a viable approach to avoid this behavior without risking to compromise the core measuring logic of the control. Additionally the same behavior can also be observed with the native MS DataGrid control. 

Regards,
Vladimir Stoyanov
Progress Telerik