I discovered a strange problem to do with double buffering and selection.
When I draw my scene I always end by swapping the buffers, and of course I enabled GLUT_DOUBLE at the outset.
However when I get a mouse click I need to re-draw the scene for selection to get the x,y,z of the triangles that intersect my x,y location.
What I find is that when I do this, the on-screen image momentarily goes to the wrong buffer, which looks bad.
Does anybody know how I can fix this?