fix: Indicate selected item in NavigationView

- Fixes #4794 - ensures the pre-selected NavigationView item is indicated after loading

Author: MartinZikmund

src/SamplesApp/SamplesApp.Shared/App.xaml.cs

@@ -210,7 +210,10 @@ override async void OnActivated(IActivatedEventArgs e)
 					$"PreviousState - {e.PreviousExecutionState}, " +
 					$"Uri - {protocolActivatedEventArgs.Uri}",
 					"Application activated via protocol");
+#if !__SKIA__
+				// TODO: Re-enable when #4810 is closed
 				await dlg.ShowAsync();
+#endif
 			}
 		}
 
@@ -254,7 +257,10 @@ private async void DisplayLaunchArguments(LaunchActivatedEventArgs launchActivat
 			if (!string.IsNullOrEmpty(launchActivatedEventArgs.Arguments))
 			{
 				var dlg = new MessageDialog(launchActivatedEventArgs.Arguments, "Launch arguments");
+#if !__SKIA__
+				// TODO: Re-enable when #4810 is closed
 				await dlg.ShowAsync();
+#endif
 			}
 		}
 

src/SamplesApp/UITests.Shared/Microsoft_UI_Xaml_Controls/NavigationViewTests/NavigationViewBasicPage.xaml

@@ -12,7 +12,7 @@
     <Grid>
 		<mux:NavigationView x:Name="NavigationViewControl">
 			<mux:NavigationView.MenuItems>
-				<mux:NavigationViewItem Content="A" x:Name="A" />
+				<mux:NavigationViewItem IsSelected="True" Content="A" x:Name="A" />
 				<mux:NavigationViewItem Content="B" x:Name="B" />
 				<mux:NavigationViewItem Content="C" x:Name="C" />
 			</mux:NavigationView.MenuItems>

src/Uno.UI/Microsoft/UI/Xaml/Controls/NavigationView/NavigationView.cs

@@ -1375,8 +1375,12 @@ int GetChildDepth(NavigationViewRepeaterPosition position, NavigationViewItemBas
 					});
 				}
 
+#if IS_UNO
 				// TODO: Uno specific - remove when #4689 is fixed
+				// This ensures the item is properly initialized and the selected item is displayed
 				nvibImpl.Reinitialize();
+				AnimateSelectionChanged(SelectedItem);
+#endif
 			}
 		}
 
@@ -5804,7 +5808,7 @@ private bool IsTopLevelItem(NavigationViewItemBase nvib)
 			return IsRootItemsRepeater(GetParentItemsRepeaterForContainer(nvib));
 		}
 
-		#region Uno specific
+#region Uno specific
 
 		//TODO: Uno specific - remove when #4689 is fixed
 
@@ -5824,6 +5828,6 @@ private void SetHeaderContentMinHeight(double minHeight)
 			}
 		}
 
-		#endregion
+#endregion
 	}
 }

src/Uno.UI/UI/Xaml/UIElement.Layout.netstd.cs

@@ -115,6 +115,7 @@ public void Arrange(Rect finalRect)
 			{
 				LayoutInformation.SetLayoutSlot(this, finalRect);
 				HideVisual();
+				_isArrangeValid = true;
 				return;
 			}