Fix #15: close finding pane reliably; Fix #16: exit Compare when opening Apps (#17)

- #15: BtnCloseFinding now uses a code-behind Click handler that clears
  OverviewFindingsList.SelectedItem before nulling SelectedFinding, so
  the ListView TwoWay binding can't immediately re-push the old
  selection back into the VM.
- #16: NavView_ItemInvoked case 'apps' now exits Compare and Settings
  modes (matching cases 'compare' and 'settings'), so opening the Apps
  pane on top of an active Compare view hides the Compare sub-panel.

Closes #15, closes #16.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: aclinick

MSIXplainer/MainPage.xaml

@@ -356,7 +356,8 @@
                                 <!-- All findings -->
                                 <TextBlock Text="All Findings" Style="{StaticResource SubtitleTextBlockStyle}" />
 
-                                <ListView AutomationProperties.AutomationId="OverviewFindingsList"
+                                <ListView x:Name="OverviewFindingsList"
+                                          AutomationProperties.AutomationId="OverviewFindingsList"
                                           ItemsSource="{x:Bind ViewModel.CategoryFindings, Mode=OneWay}"
                                           SelectedItem="{x:Bind ViewModel.SelectedFinding, Mode=TwoWay}"
                                           SelectionMode="Single">
@@ -519,9 +520,10 @@
                                     <!-- Close button -->
                                     <Button AutomationProperties.AutomationId="BtnCloseFinding"
                                             HorizontalAlignment="Right"
-                                            Command="{x:Bind ViewModel.DismissSelectedFindingCommand}"
+                                            Click="OnCloseFindingClick"
                                             Padding="4" MinWidth="0" MinHeight="0"
-                                            Background="Transparent" BorderThickness="0">
+                                            Background="Transparent" BorderThickness="0"
+                                            ToolTipService.ToolTip="Close">
                                         <FontIcon Glyph="&#xE711;" FontSize="12" />
                                     </Button>
 

MSIXplainer/MainPage.xaml.cs

@@ -97,6 +97,8 @@ private async void NavView_ItemInvoked(NavigationView sender, NavigationViewItem
         switch (invoked.Tag)
         {
             case "apps":
+                ExitCompareMode();
+                ExitSettingsMode();
                 await OpenAppsPaneAsync();
                 break;
 
@@ -195,6 +197,17 @@ private void ViewFinding_Click(object sender, RoutedEventArgs e)
             ViewModel.SelectedFinding = finding;
     }
 
+    /// <summary>
+    /// Closes the finding detail pane. Clears the OverviewFindingsList selection
+    /// explicitly first so the TwoWay binding can't immediately re-push the old
+    /// selection back into ViewModel.SelectedFinding once we null it.
+    /// </summary>
+    private void OnCloseFindingClick(object sender, RoutedEventArgs e)
+    {
+        OverviewFindingsList.SelectedItem = null;
+        ViewModel.SelectedFinding = null;
+    }
+
     /// <summary>
     /// Copies a manifest property value to the clipboard. Wraps the clipboard
     /// call in try/catch so a transient clipboard failure never bubbles up as