message: Set non-transparent background if OS doesn't support acrylic blur behind (win)
diff: @@ -913,6 +913,10 @@ namespace TogglDesktop
  {
  Win32.EnableBlurBehind(this.interopHelper.Handle);
  }
  + else
  + {
  + this.SetResourceReference(Window.BackgroundProperty, "Toggl.Background");
  + }
  }
  #endregion
  