Hidden windows may be displayed using RadDock.DisplayWindow API. It will take the last DockState for the specified DockWindow (before it got hidden) and restore it.
Currently our QuickNavigator is a window activation tool (much like in Visual Studio) and does not allow for displaying already hidden windows. This however is a nice-to-have feature and we will consider implementing it in future.
I would like to thank you for your feedback which is of great help to us.
the Telerik team