Indeed, we had some drawing issues related to RadForm (and RadMessageBox respectively) in the past. However, these issues should have already been addressed in our latest versions and I am not able to replicate them, neither on my local machine, nor through RDP. So, could you please try to update your Telerik version to the latest one - Q1 2011 SP1 (v2011.1.11.419)? Let us know if you continue experiencing any issues.
the Telerik team
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