RadDock version 423 is quite different from the current version 621. On the other hand, we never experienced problems, such yours with any of the versions, posted in the forum and that's why we asked for a test application which could be used to observe the problem. Again, I kindly ask you for a simple application which will be immediately tested by a developer. We will respond with a solution or a suggestion as soon as we find one.
Valeri Hristov (Senior Developer, MCSD)
the Telerik team