amend: Child window visibility handling

2dust#6596

When the main window is hidden, open child windows are mistakenly hidden as well.
This prevents reopening child windows after the main window is shown again.

v2rayN/v2rayN.Desktop/Views/MainWindow.axaml.cs

@@ -390,7 +390,6 @@ private async void MenuClose_Click(object? sender, RoutedEventArgs e)
             StorageUI();
 
 	        await ViewModel?.MyAppExitAsync(false);
-	        Close();
         }
 
         #endregion Event
@@ -414,6 +413,10 @@ public void ShowHideWindow(bool? blShow)
 	        {
 		        if (Utils.IsOSX() || _config.UiItem.Hide2TrayWhenClose)
 		        {
+			        foreach (var ownedWindow in this.OwnedWindows.ToList())
+			        {
+				        ownedWindow.Close();
+			        }
 			        this.Hide();
 		        }
 		        else
@@ -492,4 +495,4 @@ private void MenuItem_Click(object? sender, RoutedEventArgs e)
 
         #endregion UI
     }
-}
+}