A possible workaround has been demonstrated in the attached project.

Resizing a RadPane's splitter while its Header's or Content's ContextMenu is opened leads to incorrect resize

When a pane is unpinned, mouse over it in order to show. After that when the mouse is removed from the pane it flickers before the animation is started.

Add shortcuts like:
- close a pane by mousewheel click on the tab
- close the active pane by keyboard shortcut (e.g. Ctrl + W)
- switch active pane by Ctrl + Tab

Show a navigation window for navigating between panes when the user presses Ctrl+tab. 

RadDock for WinForms has such feature: https://docs.telerik.com/devtools/winforms/dock/architecture-and-features/quick-navigator

The RadDocking control is not registering position changes of the docking window when RadDocking is in a WPF UserControl embedded in a WinForms ElementHost:

This appears to only apply to the main window; if you (at runtime) move one of the example panes into a separate window, the compass on that window displays in the correct position when you undock the other pane:

I've attached a stripped down solution that reproduces the issue (originally noticed using 2018R2 when rewriting legacy VB WinForms in C# WPF user controls as part of a tech refresh; attached demo is using 2020R2 .NET 4.5 binaries).

Application theme:

StyleManager.ApplicationTheme = new CrystalTheme();

Docking theme:

<telerik:RadDocking Grid.Row="2" telerik:StyleManager.Theme="Office2016">
	<telerik:RadDocking.DocumentHost >
		<telerik:RadSplitContainer>
			<telerik:RadPaneGroup>
				<telerik:RadPane Header="Description">
					<TextBlock TextWrapping="Wrap" Text="On the Documents tab above press Ctrl + Mouse Left button to display the Popup Menu. You can use the same combination on every tab."/>
				</telerik:RadPane>
			</telerik:RadPaneGroup>
		</telerik:RadSplitContainer>
	</telerik:RadDocking.DocumentHost>
	<telerik:RadSplitContainer InitialPosition="DockedBottom">
		<telerik:RadPaneGroup>
			<telerik:RadPane Header="NonDraggable">
				<TextBlock TextWrapping="Wrap" Text="This pane cannot be dragged, because it has its property CanFloat set 'False'."/>
			</telerik:RadPane>
		</telerik:RadPaneGroup>
	</telerik:RadSplitContainer>
</telerik:RadDocking>

Like RanTabControl

Need this for an application with lots of tabs wich would not fit in the top or bottom template.

Maybe it works with a customizable TabStripTemplate where i can implement e.g. a GridView or something

Like this with a scrollbar (used TabControl PRISM example for this)