Bunch of changes for ItemsView and threads.

Wino.Mail.WinUI/AppShell.xaml

@@ -3,7 +3,6 @@
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
     xmlns:abstract="using:Wino.Views.Abstract"
-    xmlns:advanced="using:Wino.Controls.Advanced"
     xmlns:animatedvisuals="using:Microsoft.UI.Xaml.Controls.AnimatedVisuals"
     xmlns:animations="using:CommunityToolkit.WinUI.Animations"
     xmlns:controls="using:Wino.Controls"
@@ -356,7 +355,6 @@
     <Grid
         x:Name="RootGrid"
         Padding="0"
-        Background="{ThemeResource WinoApplicationBackgroundColor}"
         ColumnSpacing="0"
         RowSpacing="0">