   GLUT up key problem
  I've been having some difficulty handling a multiple key press with the Up key held down. This is the code I have to handle it:bool keys[256];int UP_KEY = 128;int LEFT_KEY = 129;int RIGHT_KEY = 130;void keyboardDown(unsigned char key, int x, int y){    keys[(int)key] = false;}void keyboardUp(unsigned char key, int x, int y){    keys[(int)key] = false;}void specialKeyboardDown(int key, int x, int y){    switch (key)    {   case GLUT_KEY_LEFT:  keys[LEFT_KEY] = true;  break;   case GLUT_KEY_RIGHT:  keys[RIGHT_KEY] = true;  break;   case GLUT_KEY_UP:  keys[UP_KEY] = true;  break;    }}void specialKeyboardUp(int key, int x, int y){    switch (key)    {   case GLUT_KEY_LEFT:  keys[LEFT_KEY] = false;  break;   case GLUT_KEY_RIGHT:  keys[RIGHT_KEY] = false;  break;   case GLUT_KEY_UP:  keys[UP_KEY] = false;  break;    }}void processKeys(){    if(keys[LEFT_KEY])   cout << LEFT_KEY << endl;    if(keys[RIGHT_KEY])   cout << RIGHT_KEY << endl;    if(keys[UP_KEY])   cout << UP_KEY << endl;    if(keys[32])   cout << 32 << endl;}int main(int argc, char **argv){    glutInit(&argc, argv);    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);    glutSpecialFunc(specialKeyboardDown);    glutKeyboardFunc(keyboard);    glutSpecialUpFunc(specialKeyboardUp);    glutKeyboardUpFunc(keyboardUp);    glutMainLoop();}Pretty basic. Here's the deal, this all works just fine on my computer, but when I sent it to 2 other people and they are unable to press Up and Spacebar together (but Left and Right work fine). Then I sent it to someone else, and it works fine on his computer. Is there something I'm missing which is system dependent?   
  It is, unfortunately, a hardware limitation on how keyboards are made. Depending on the maker of the keyboard, combinations that will work OK for some will not work for others.   ;  There has to be a workaround, right?I should probably mention, the code I gave is not the full code. The program actually worked on their computers before I added more stuff. As such, I believed it could have been a memory leak or some other fault on my part, but I checked all that and it seems ok. I switched the key from Up to 'W', and sure enough everything works fine, which proves its probably a keyboard problem.What other reason would there be for it to suddenly stop working?   