I have just chased to ground an extremely annoying bug in which for some demonstrations, bringing up a menu would cause the rest of the display to disappear. I traced it to the "fgDisplayMenu" function, where the matrices were being set and popped at the end. As it now stands, freeglut first sets the matrix mode to GL_MODELVIEW and pops the matrix and then sets the matrix mode to GL_PROJECTION and pops the matrix. I switched it so that it sets the matrix mode to GL_PROJECTION first and pops the matrix and then sets the matrix mode to GL_MODELVIEW and pops the matrix. To the best of my knowledge the only difference is that control leaves the function with the matrix mode as GL_MODELVIEW instead of as GL_PROJECTION. Does anybody know where else in freeglut this might mess things up?
John F. Fay