RadGrid for ASP.NET AJAX supports adjusting the position of the filter menu based on the viewport bounds. You can refer to the RadGrid Basic Filterin Demo
. If you shrink the width and height of your browser window and click on a filter icon close the bottom right edge you will see the position of the filtering menu adjusted. If you are using an older version of RadControls, consider upgrading to the latest to benefit from advanced functionality, better support and constant improvement.
the Telerik team