Merge branch 'master' into fixes/enable-existing-nullable-errors

Avalonia.sln

@@ -60,7 +60,6 @@ EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Shared", "Shared", "{A689DEF5-D50F-4975-8B72-124C9EB54066}"
 	ProjectSection(SolutionItems) = preProject
 		.editorconfig = .editorconfig
-		src\Shared\SharedAssemblyInfo.cs = src\Shared\SharedAssemblyInfo.cs
 	EndProjectSection
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Avalonia.ReactiveUI", "src\Avalonia.ReactiveUI\Avalonia.ReactiveUI.csproj", "{6417B24E-49C2-4985-8DB2-3AB9D898EC91}"

src/Avalonia.X11/X11Window.cs

@@ -785,6 +785,12 @@ namespace Avalonia.X11
 
         void Cleanup()
         {
+            if (_transparencyHelper != null)
+            {
+                _transparencyHelper.Dispose();
+                _transparencyHelper = null;
+            }
+            
             if (_imeControl != null)
             {
                 _imeControl.Dispose();