There is a behavior we're aware of in design time. When you build the project with the form open in design-time, the VS designer appears to alter the layout. However, these changes are not serialized, nor do they appear in runtime.
You can switch the active window to code view before building your project in order to avoid this effect.
Did you try to build the project when the form container isn't active and then re-open the form container or to resize the control after it appears incorrectly? Does the control show this behavior in both design time and run-time?
Please start a support ticket and send us a sample project allowing us to reproduce this behavior.
Thank you for writing. We're looking forward to your reply.
the Telerik team