drawing on/in gamewindow

I am unable to solve drawing lines on the gamewindow. The help seems to suggest that a background file image is the only way (this indicates being pre-drawn). Drawing on the form puts the lines behind the gamewindow.
Are there any suggestions please?

It is currently impossible to draw directly on the background of the gamewindow.
Maybe in the next update of this library it will be possible.

Thanks Erel, I look forward to it.