feat: ultimate refactoring to separate default dialog and custom dialog.

src/Ursa/Common/EventHelper.cs

@@ -0,0 +1,23 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+
+namespace Ursa.Common;
+
+internal static class EventHelper
+{
+    public static void RegisterClickEvent(EventHandler<RoutedEventArgs> handler, params Button?[] buttons)
+    {
+        foreach (var button in buttons)
+        {
+            if(button is not null) button.Click += handler;
+        }
+    }
+    
+    public static void UnregisterClickEvent(EventHandler<RoutedEventArgs> handler, params Button?[] buttons)
+    {
+        foreach (var button in buttons)
+        {
+            if(button is not null) button.Click -= handler;
+        }
+    }
+}