[WP8] CustomMessageBox dismissal no longer causes black SystemTray

The CustomMessageBox was having an interaction with WP8 where its
dismissal was changing the SystemTray's background color to black. It
appears that the SystemTray's background color was never set, despite
its appearing white prior to the use of a CustomMessageBox.

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla25234.cs

@@ -0,0 +1,35 @@
+using System;
+
+using Xamarin.Forms.CustomAttributes;
+
+#if UITEST
+using Xamarin.UITest;
+using NUnit.Framework;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Bugzilla, 25234, "Use of CustomMessageBox resets SystemTray BackgroundColor to black", PlatformAffected.WinPhone)]
+	public class Bugzilla25234 : TestContentPage
+	{
+		protected override void Init()
+		{
+			Content = new StackLayout
+			{
+				Children =
+				{
+					new Button
+					{
+						Text = "Click for Alert",
+						Command = new Command(() =>
+						{
+							DisplayAlert("Display Alert",
+								"If the theme is set to light on WP8, the status bar should return to the white color when closed", "OK");
+						})
+					}
+				}
+			};
+		}
+	}
+}

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems

@@ -19,6 +19,7 @@
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla22401.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla24769.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Bugzilla25234.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla25662.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla26501.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla26868.cs" />

Xamarin.Forms.Platform.WP8/Platform.cs

@@ -42,6 +42,7 @@ namespace Xamarin.Forms.Platform.WinPhone
 
 			_renderer = new Canvas();
 			_renderer.SizeChanged += RendererSizeChanged;
+			_renderer.Loaded += (sender, args) => UpdateSystemTray();
 
 			_tracker.CollectionChanged += (sender, args) => UpdateToolbarItems();
 
@@ -483,6 +484,15 @@ namespace Xamarin.Forms.Platform.WinPhone
 			}
 		}
 
+		void UpdateSystemTray()
+		{
+			var lightThemeVisibility = (Visibility)System.Windows.Application.Current.Resources["PhoneLightThemeVisibility"];
+			if (lightThemeVisibility == Visibility.Visible && SystemTray.BackgroundColor == System.Windows.Media.Color.FromArgb(0, 0, 0, 0))
+			{
+				SystemTray.BackgroundColor = System.Windows.Media.Color.FromArgb(1, 255, 255, 255);
+			}
+		}
+
 		void UpdateToolbarItems()
 		{
 			if (_page.ApplicationBar == null)