I am not quite sure I understand the problem. The provided screenshot displays a very basic declaration of RadSplitter on the page. Could you please provide more detailed information on the specific problem, a sample page demonstrating the problem along with screenshots of the expected behavior?
In general, RadSplitter and RadPane are content containers and they do not have noticable visual representation. On the other hand, RadSlidingPane's and RadSplitBar's do have a visual representation, because they provide functionality that requires user interaction. You can find detailed information regarding the RadSplitter and its child controls in our online documentation
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