Hi,
I moved away my .gnubg to remove all my preferred settings. Open gnubg and do the following:
Settings-->Appearance-->General and select 3d Board.
Then click Chequers followed by Chequer 0:
Move the Shine slider and press OK.
Click on Chequer 0: again and you get
set gui showids on
(No game) (No game) error: xp_attach_gl_context returned: 2
(gnubg:44197): GdkGLExt-WARNING **: glXMakeCurrent() failed
Move the slider again and press OK and you may get corrupted graphics in the Custom Design preview window.
Louis