The mentioned forum thread from the RadSplitter for ASP.NET forums, not RadSplitter for ASP.NET AJAX. None AJAX RadSplitter does support Right-To-Left direction.
In the provided sample page I noticed that you are using RadControls for ASP.NET AJAX, however, I was unable to reproduce the problem using the latest version Q2 2010 SP2 (please find the attached image demonstrating the provided page on my). Could you please upgrade to the latest official version and see if the problem still exists. If so, could you please open a support ticket and provide a simple runnable project reproducing the problem?
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