When a pane goes floating, actually it is placed in a chromeless window. Unfortunately, placing a WindowsFormsHost in a chromeless window is not supported scenario in WPF. If you debug it, you will see that the host is still there, but it is not visible. This is a limitation of the RadDocking at this stage. We sorry for any inconvenience caused.
We consider targeting this problem, but this limitation is located very deep in the architecture of the RadDocking and this makes the issue hard to be fixed.
the Telerik team
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