I believe this issue is discussed in this thread
. I am pasting the answer again here as we try to keep the other thread as clean as possible and your question is not closely related to the PortalSite example but more to a general work with the control:"In Valeri's example the docks are first added to a hidden update
panel and then moved to a zone. To add the dock to the page without
adding it to a zone one option is to simply add the dock to the update
but you need to make the panel visible.
The other possibility is to directly add them the RadDockLayout as I explained in this thread
without using the hidden update panel at all. I am attaching a simple
page demonstrating this possibility. Please, note that my page is just
an example and there is no preservation of state or recreation of the
objects - it merely adds dynamically a dock to the page."
the Telerik team