Make the GTK stuff build again.

Gtk/Perspex.Gtk/GtkPlatform.cs

@@ -45,6 +45,11 @@ namespace Perspex.Gtk
             locator.Register(() => instance, typeof(IPlatformThreadingInterface));
         }
 
+        public bool HasMessages()
+        {
+            return Gtk.Application.EventsPending();
+        }
+
         public void ProcessMessage()
         {
             Gtk.Application.RunIteration();

Gtk/Perspex.Gtk/Perspex.Gtk.csproj

@@ -65,6 +65,10 @@
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <ItemGroup>
+    <ProjectReference Include="..\..\Perspex.Animation\Perspex.Animation.csproj">
+      <Project>{d211e587-d8bc-45b9-95a4-f297c8fa5200}</Project>
+      <Name>Perspex.Animation</Name>
+    </ProjectReference>
     <ProjectReference Include="..\..\Perspex.Base\Perspex.Base.csproj">
       <Project>{B09B78D8-9B26-48B0-9149-D64A2F120F3F}</Project>
       <Name>Perspex.Base</Name>

TestApplication/Program.cs

@@ -504,7 +504,7 @@ namespace TestApplication
                             RenderTransform = new RotateTransform(),
                             PropertyTransitions = new PropertyTransitions
                             {
-                                Rectangle.WidthProperty.Transition(1000),
+                                Rectangle.WidthProperty.Transition(300),
                                 Rectangle.HeightProperty.Transition(1000),
                             },
                             [Grid.ColumnProperty] = 1,

TestApplication/TestApplication-Mono.csproj

@@ -79,6 +79,10 @@
       <Project>{FB05AC90-89BA-4F2F-A924-F37875FB547C}</Project>
       <Name>Perspex.Cairo</Name>
     </ProjectReference>
+    <ProjectReference Include="..\Perspex.Animation\Perspex.Animation.csproj">
+      <Project>{d211e587-d8bc-45b9-95a4-f297c8fa5200}</Project>
+      <Name>Perspex.Animation</Name>
+    </ProjectReference>
     <ProjectReference Include="..\Perspex.Application\Perspex.Application.csproj">
       <Project>{799A7BB5-3C2C-48B6-85A7-406A12C420DA}</Project>
       <Name>Perspex.Application</Name>