Most probably the TreeView control that you have placed in the RadSlidingPane uses "position:relative". If this is the case, you have to apply that positioning to the element that you scroll. The CSS class, applied to that element is rspSlideContent
. For example:
In case this does not help, I will need a simple running project, demonstrating the problem, so that I can research what is causing it locally.
the Telerik team