Proper handling of DateTimeOffset, support for Multi-Day events and reacting to adding/removing events for the days.

Wino.Calendar/Services/AccountCalendarStateService.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Linq;
 using CommunityToolkit.Mvvm.ComponentModel;
@@ -21,6 +22,16 @@ namespace Wino.Calendar.Services
 
         private ObservableCollection<GroupedAccountCalendarViewModel> _internalGroupedAccountCalendars = new ObservableCollection<GroupedAccountCalendarViewModel>();
 
+        public IEnumerable<AccountCalendarViewModel> ActiveCalendars
+        {
+            get
+            {
+                return GroupedAccountCalendars
+                .SelectMany(a => a.AccountCalendars)
+                .Where(b => b.IsChecked);
+            }
+        }
+
         public AccountCalendarStateService()
         {
             GroupedAccountCalendars = new ReadOnlyObservableCollection<GroupedAccountCalendarViewModel>(_internalGroupedAccountCalendars);