You can add that behavior to your Dock by adding the following code to your instance:
<telerik:RadDocking.FlyoutBehavior>
<telerik:ClickFlyoutBehavior />
</telerik:RadDocking.FlyoutBehavior>
To help illustrate this, I've written a sample application that demonstrates the behavior.
Open the app and run it, you'll see two instances of Dock on MainPage.xaml. The one the left uses the built-in ClickFlyoutBehavior. The dock on the right will show you how to add animation to the flyout via the AnimatedClickFlyout behavior class.
Thank you for contacting Support and thank you for choosing Telerik.
Regards,
Lance
Telerik
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