Fixing the leak in calendar mmode.

Wino.Mail.WinUI/Controls/Calendar/CalendarPeriodControl.xaml

@@ -11,6 +11,7 @@
     xmlns:viewModels="using:Wino.Calendar.ViewModels.Data"
     x:Name="Root"
     SizeChanged="ControlSizeChanged"
+    Unloaded="ControlUnloaded"
     mc:Ignorable="d">
 
     <UserControl.Resources>

Wino.Mail.WinUI/Controls/Calendar/CalendarPeriodControl.xaml.cs

@@ -324,6 +324,13 @@ public sealed partial class CalendarPeriodControl : UserControl, INotifyProperty
         });
     }
 
+    private void ControlUnloaded(object sender, RoutedEventArgs e)
+    {
+        DetachCurrentItemsSource();
+        _sizeRefreshTimer.Stop();
+        _sizeRefreshTimer.Tick -= SizeRefreshTimerTick;
+    }
+
     private void SizeRefreshTimerTick(DispatcherQueueTimer sender, object args)
     {
         sender.Stop();