Fix couple issues with starting mode.

Wino.Mail.WinUI/Controls/Calendar/WinoCalendarControl.cs

@@ -221,10 +221,17 @@ public partial class WinoCalendarControl : Control
     }
 
     private void UpdateIdleState()
+    {
+        if (InternalFlipView != null)
         {
             InternalFlipView.Opacity = IsFlipIdle ? 0 : 1;
+        }
+
+        if (IdleGrid != null)
+        {
             IdleGrid.Visibility = IsFlipIdle ? Visibility.Visible : Visibility.Collapsed;
         }
+    }
 
     private void ActiveTimelineCellUnselected(object sender, TimelineCellUnselectedArgs e)
         => TimelineCellUnselected?.Invoke(this, e);

Wino.Mail.WinUI/Controls/Calendar/WinoCalendarFlipView.cs

@@ -49,6 +49,8 @@ public partial class WinoCalendarFlipView : CustomCalendarFlipView
 
     internal event EventHandler<ProgrammaticNavigationCompletedEventArgs>? ProgrammaticNavigationCompleted;
 
+    private INotifyCollectionChanged? _trackedItemsSource;
+
     public WinoCalendarFlipView()
     {
         RegisterPropertyChangedCallback(ItemsSourceProperty, new DependencyPropertyChangedCallback(OnItemsSourceChanged));
@@ -64,10 +66,19 @@ public partial class WinoCalendarFlipView : CustomCalendarFlipView
 
     private void RegisterItemsSourceChange()
     {
-        if (GetItemsSource() is INotifyCollectionChanged notifyCollectionChanged)
+        if (_trackedItemsSource != null)
         {
-            notifyCollectionChanged.CollectionChanged += ItemsSourceUpdated;
+            _trackedItemsSource.CollectionChanged -= ItemsSourceUpdated;
         }
+
+        _trackedItemsSource = GetItemsSource();
+
+        if (_trackedItemsSource != null)
+        {
+            _trackedItemsSource.CollectionChanged += ItemsSourceUpdated;
+        }
+
+        UpdateIdleState();
     }
 
     protected override void OnSelectedItemChanged(object oldValue, object newValue)
@@ -92,7 +103,13 @@ public partial class WinoCalendarFlipView : CustomCalendarFlipView
 
     private void ItemsSourceUpdated(object sender, NotifyCollectionChangedEventArgs e)
     {
-        IsIdle = e.Action == NotifyCollectionChangedAction.Reset || e.Action == NotifyCollectionChangedAction.Replace;
+        UpdateIdleState();
+    }
+
+    private void UpdateIdleState()
+    {
+        var itemsSource = GetItemsSource();
+        IsIdle = itemsSource == null || itemsSource.Count == 0;
     }
 
     private void UpdateActiveElements()

Wino.Mail.WinUI/Services/AccountCalendarStateService.cs

@@ -25,6 +25,8 @@ public partial class AccountCalendarStateService : ObservableRecipient,
     IRecipient<CalendarListDeleted>,
     IRecipient<AccountRemovedMessage>
 {
+    private readonly object _calendarStateLock = new();
+
     public IDispatcher? Dispatcher { get; set; }
 
     public event EventHandler<GroupedAccountCalendarViewModel>? CollectiveAccountGroupSelectionStateChanged;
@@ -42,19 +44,27 @@ public partial class AccountCalendarStateService : ObservableRecipient,
     public IEnumerable<AccountCalendarViewModel> ActiveCalendars
     {
         get
+        {
+            lock (_calendarStateLock)
             {
                 return _internalGroupedAccountCalendars
                     .SelectMany(a => a.AccountCalendars)
-                .Where(b => b.IsChecked);
+                    .Where(b => b.IsChecked)
+                    .ToList();
+            }
         }
     }
 
     public IEnumerable<AccountCalendarViewModel> AllCalendars
     {
         get
+        {
+            lock (_calendarStateLock)
             {
                 return _internalGroupedAccountCalendars
-                .SelectMany(a => a.AccountCalendars);
+                    .SelectMany(a => a.AccountCalendars)
+                    .ToList();
+            }
         }
     }
 
@@ -83,6 +93,8 @@ public partial class AccountCalendarStateService : ObservableRecipient,
         => AccountCalendarSelectionStateChanged?.Invoke(this, e);
 
     public void AddGroupedAccountCalendar(GroupedAccountCalendarViewModel groupedAccountCalendar)
+    {
+        lock (_calendarStateLock)
         {
             groupedAccountCalendar.CalendarSelectionStateChanged += SingleCalendarSelectionStateChanged;
             groupedAccountCalendar.CollectiveSelectionStateChanged += SingleGroupCalendarCollectiveStateChanged;
@@ -103,8 +115,11 @@ public partial class AccountCalendarStateService : ObservableRecipient,
                 }
             }
         }
+    }
 
     public void RemoveGroupedAccountCalendar(GroupedAccountCalendarViewModel groupedAccountCalendar)
+    {
+        lock (_calendarStateLock)
         {
             groupedAccountCalendar.CalendarSelectionStateChanged -= SingleCalendarSelectionStateChanged;
             groupedAccountCalendar.CollectiveSelectionStateChanged -= SingleGroupCalendarCollectiveStateChanged;
@@ -126,16 +141,22 @@ public partial class AccountCalendarStateService : ObservableRecipient,
                 }
             }
         }
+    }
 
     public void ClearGroupedAccountCalendars()
+    {
+        lock (_calendarStateLock)
         {
             while (_internalGroupedAccountCalendars.Any())
             {
                 RemoveGroupedAccountCalendar(_internalGroupedAccountCalendars[0]);
             }
         }
+    }
 
     public void AddAccountCalendar(AccountCalendarViewModel accountCalendar)
+    {
+        lock (_calendarStateLock)
         {
             // Find the group that this calendar belongs to.
             var group = _internalGroupedAccountCalendars.FirstOrDefault(g => g.Account.Id == accountCalendar.Account.Id);
@@ -162,8 +183,11 @@ public partial class AccountCalendarStateService : ObservableRecipient,
                 }
             }
         }
+    }
 
     public void RemoveAccountCalendar(AccountCalendarViewModel accountCalendar)
+    {
+        lock (_calendarStateLock)
         {
             var group = _internalGroupedAccountCalendars.FirstOrDefault(g => g.Account.Id == accountCalendar.Account.Id);
 
@@ -189,6 +213,7 @@ public partial class AccountCalendarStateService : ObservableRecipient,
                 RemoveGroupedAccountCalendar(group);
             }
         }
+    }
 
     public async void Receive(CalendarListAdded message)
     {
@@ -289,7 +314,11 @@ public partial class AccountCalendarStateService : ObservableRecipient,
         {
             await Dispatcher.ExecuteOnUIThread(() =>
             {
-                var groupedAccount = _internalGroupedAccountCalendars.FirstOrDefault(a => a.Account.Id == removedAccountId);
+                GroupedAccountCalendarViewModel? groupedAccount;
+                lock (_calendarStateLock)
+                {
+                    groupedAccount = _internalGroupedAccountCalendars.FirstOrDefault(a => a.Account.Id == removedAccountId);
+                }
 
                 if (groupedAccount != null)
                 {
@@ -299,7 +328,11 @@ public partial class AccountCalendarStateService : ObservableRecipient,
         }
         else
         {
-            var groupedAccount = _internalGroupedAccountCalendars.FirstOrDefault(a => a.Account.Id == removedAccountId);
+            GroupedAccountCalendarViewModel? groupedAccount;
+            lock (_calendarStateLock)
+            {
+                groupedAccount = _internalGroupedAccountCalendars.FirstOrDefault(a => a.Account.Id == removedAccountId);
+            }
 
             if (groupedAccount != null)
             {

Wino.Mail.WinUI/Services/NavigationService.cs

@@ -35,6 +35,21 @@ public class NavigationService : NavigationServiceBase, INavigationService
         WinoPage.ComposePage
     };
 
+    private static readonly WinoPage[] MailOnlyPages =
+    [
+        WinoPage.MailListPage,
+        WinoPage.MailRenderingPage,
+        WinoPage.ComposePage,
+        WinoPage.IdlePage,
+        WinoPage.WelcomePage
+    ];
+
+    private static readonly WinoPage[] CalendarOnlyPages =
+    [
+        WinoPage.CalendarPage,
+        WinoPage.EventDetailsPage
+    ];
+
     public NavigationService(IStatePersistanceService statePersistanceService)
     {
         _statePersistanceService = statePersistanceService;
@@ -140,9 +155,17 @@ public class NavigationService : NavigationServiceBase, INavigationService
         var pageType = GetPageType(page);
         if (pageType == null) return false;
 
-        var currentApplicationMode = GetCoreFrame(NavigationReferenceFrame.ShellFrame)?.Content?.GetType() == typeof(MailAppShell)
-            ? WinoApplicationMode.Mail
-            : WinoApplicationMode.Calendar;
+        var currentApplicationMode = _statePersistanceService.ApplicationMode;
+
+        if (currentApplicationMode == WinoApplicationMode.Calendar && IsMailOnlyPage(page))
+        {
+            return false;
+        }
+
+        if (currentApplicationMode == WinoApplicationMode.Mail && IsCalendarOnlyPage(page))
+        {
+            return false;
+        }
 
         _statePersistanceService.IsReadingMail = _renderingPageTypes.Contains(page);
         _statePersistanceService.IsEventDetailsVisible = page == WinoPage.EventDetailsPage;
@@ -248,6 +271,12 @@ public class NavigationService : NavigationServiceBase, INavigationService
         return false;
     }
 
+    private static bool IsMailOnlyPage(WinoPage page)
+        => MailOnlyPages.Contains(page);
+
+    private static bool IsCalendarOnlyPage(WinoPage page)
+        => CalendarOnlyPages.Contains(page);
+
     private static LoadCalendarMessage CreateLoadCalendarMessage(CalendarPageNavigationArgs args)
     {
         var targetDate = args.RequestDefaultNavigation