You can try to use SuspendLayout / ResumeLayout methods before and after loading operation to achieve this functionality. Another solution is to create Panel in front of RadDock control and after the layout is loaded remove this dummy Panel control. Since the layout operation is an asynchronous operation, it may not be ready right after the LoadFromXml call. This is why you can keep the panel visible for a few seconds after the LoadFromXml call, using a Timer. I should admit that this is not a nice solution, but it is the only one I can provide for an issue of this kind.
I hope this helps. Do not hesitate to contact us if you have further questions or issues.
the Telerik team
Q2’11 SP1 of RadControls for WinForms is available for download (see what's new); also available is the Q3'11 Roadmap for Telerik Windows Forms controls.