Question About glut and OpenGL

[shortyzms]

I have been trying to write a small glut program that uses popup context menus on right clicks to draw objects. However, every time I do this, the area underneath the submenu item I clicked does not refresh.

Here's a helpful test program I've found from Mindf**k's glut tutorial...

#include <iostream>
#include <GL/glut.h>
#include <cstdlib>
using namespace std;
 
void createMenu(void);
void menu(int value);
void disp(void);
 
static int win;
static int menid;
static int submenid;
static int primitive = 0;
 
int main(int argc, char **argv){
 
  // normal initialisation
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_RGBA | GLUT_SINGLE);
  glutInitWindowSize(500,500);
  glutInitWindowPosition(100,100);
 
  win = glutCreateWindow("GLUT MENU");
 
  // put all the menu functions in one nice procedure
  createMenu();
 
  // set the clearcolor and the callback
  glClearColor(0.0,0.0,0.0,0.0);
 
  glutDisplayFunc(disp);
 
  // enter the main loop
  glutMainLoop();
 
}
 
 
void createMenu(void){
  //////////
  // MENU //
  //////////
 
  // Create a submenu, this has to be done first.
  submenid = glutCreateMenu(menu);
 
  // Add sub menu entry
  glutAddMenuEntry("Teapot", 2);
  glutAddMenuEntry("Cube", 3);
  glutAddMenuEntry("Torus", 4);
 
  // Create the menu, this menu becomes the current menu
  menid = glutCreateMenu(menu);
 
  // Create an entry
  glutAddMenuEntry("Clear", 1);
 
  glutAddSubMenu("Draw", submenid);
  // Create an entry
  glutAddMenuEntry("Quit", 0);
 
  // Let the menu respond on the right mouse button
  glutAttachMenu(GLUT_RIGHT_BUTTON);
 
 
}
 
void disp(void){
  // Just clean the screen
  glClear(GL_COLOR_BUFFER_BIT);
 
  // draw what the user asked
  if(primitive == 1){
    glutPostRedisplay();
  }else if(primitive == 2){
    glutWireTeapot(0.5);
  }else if(primitive == 3){
    glutWireCube(0.5);
  }else if(primitive == 4){
    glutWireTorus(0.3,0.6,100,100);
  }
  glFlush();
}
 
 
void menu(int value){
  if(value == 0){
    glutDestroyWindow(win);
    exit(0);
  }else{
    primitive=value;
  }
 
  // you would want to redraw now
  glutPostRedisplay();
}

It's a pretty standard program, but here's what it looks like when I try to use it.

Notice that the only part of the window that fails to repaint is underneath the submenu item I clicked. This doesn't happen at all if I click a menu item. This happens with other programs I've written too using double buffering. I'm thinking it might be a problem with my video card drivers or something. Could anyone shed some light on this for me?