feat: try to use grid as panel.

demo/Ursa.Demo/ViewModels/MainViewViewModel.cs

@@ -41,6 +41,7 @@ public class MainViewViewModel : ViewModelBase
             MenuKeys.MenuKeyLoading => new LoadingDemoViewModel(),
             MenuKeys.MenuKeyMessageBox => new MessageBoxDemoViewModel(),
             MenuKeys.MenuKeyNavigation => new NavigationMenuDemoViewModel(),
+            MenuKeys.MenuKeyNavMenu => new NavMenuDemoViewModel(),
             MenuKeys.MenuKeyNumericUpDown => new NumericUpDownDemoViewModel(),
             MenuKeys.MenuKeyPagination => new PaginationDemoViewModel(),
             MenuKeys.MenuKeyRangeSlider => new RangeSliderDemoViewModel(),

demo/Ursa.Demo/ViewModels/MenuViewModel.cs

@@ -28,6 +28,7 @@ public class MenuViewModel: ViewModelBase
             new() { MenuHeader = "Loading", Key = MenuKeys.MenuKeyLoading },
             new() { MenuHeader = "Message Box", Key = MenuKeys.MenuKeyMessageBox, Status = "New" },
             new() { MenuHeader = "Navigation", Key = MenuKeys.MenuKeyNavigation, Status = "WIP" },
+            new() { MenuHeader = "Nav Menu", Key = MenuKeys.MenuKeyNavMenu, Status = "WIP"},
             new() { MenuHeader = "NumericUpDown", Key = MenuKeys.MenuKeyNumericUpDown, Status = "New" },
             new() { MenuHeader = "Pagination", Key = MenuKeys.MenuKeyPagination },
             new() { MenuHeader = "RangeSlider", Key = MenuKeys.MenuKeyRangeSlider, Status = "New"},

demo/Ursa.Demo/ViewModels/NavMenuDemoViewModel.cs

@@ -0,0 +1,8 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+
+namespace Ursa.Demo.ViewModels;
+
+public class NavMenuDemoViewModel: ObservableObject
+{
+    
+}