Initial WinUI switch.

Wino.Mail.WinUI/Selectors/MailItemDisplaySelector.cs

@@ -0,0 +1,21 @@
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+using Wino.Mail.ViewModels.Data;
+
+namespace Wino.Selectors;
+
+public partial class MailItemDisplaySelector : DataTemplateSelector
+{
+    public DataTemplate SingleMailItemTemplate { get; set; }
+    public DataTemplate ThreadMailItemTemplate { get; set; }
+
+    protected override DataTemplate SelectTemplateCore(object item, DependencyObject container)
+    {
+        if (item is MailItemViewModel)
+            return SingleMailItemTemplate;
+        else if (item is ThreadMailItemViewModel)
+            return ThreadMailItemTemplate;
+
+        return base.SelectTemplateCore(item, container);
+    }
+}