A minor tweak of the venerable rod and shelf. If Wall Line is on, you get a line at the back of the object, drawn with a dedicated Pen. This pen should match the pen of the wall. The new parameter is on by default with pen 15.
Why. Because if the shelf's plan fill is on, it tends to obscure the wall's contour. You could correct this by bringing the wall forward, but now you don't have to.
Historical note: As far as I can tell, this was my first object in GDL, with a date of 9 August 1999.