Currently when we start the application, no item is selected. Once we select one it appears as selected and we show a related pane. This is the nominal behavior of the component.
But we want to deselect it when we are clicking again on it (like in Visual Studio Code). So ideally we want a NavigationItemBehavior property with a value "Normal" and a value "Toggle".
Add a feature that allows you to open a sub menu when you click on a RadNavigationViewItem.
Similar to the hamburger menu in the Windows' Mail application.