New WinoListView implementation with multiple selections.

Wino.Mail.WinUI/Controls/ListView/WinoMailItemContainerStyleSelector.cs

@@ -0,0 +1,19 @@
+using System;
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+using Wino.Mail.ViewModels.Data;
+
+namespace Wino.Mail.WinUI.Controls.ListView;
+
+public partial class WinoMailItemContainerStyleSelector : StyleSelector
+{
+    public Style? ThreadStyle { get; set; }
+    public Style? MailItemStyle { get; set; }
+    protected override Style SelectStyleCore(object item, DependencyObject container)
+    {
+        if (item is MailItemViewModel) return MailItemStyle ?? throw new Exception($"Missing style for {nameof(MailItemViewModel)}");
+        if (item is ThreadMailItemViewModel) return ThreadStyle ?? throw new Exception($"Missing style for {nameof(ThreadMailItemViewModel)}");
+
+        return null;
+    }
+}