TGBX Visible Scene Boundary is Not Visible

TGB sets the scene background color to grey. TGBX sets the scene background to black. The black does look more cool, but now the square frames that depict the 'renderable' scene area are not visible anymore because their lines are also painted in black. You can see the lines again when you add a light colored background as shown in the image.

The easiest fix might be to paint these lights light grey over the black background.