+
+ case XK_Shift_L: special = GLUT_KEY_SHIFT_L; break;
+ case XK_Shift_R: special = GLUT_KEY_SHIFT_R; break;
+ case XK_Control_L: special = GLUT_KEY_CTRL_L; break;
+ case XK_Control_R: special = GLUT_KEY_CTRL_R; break;
+ case XK_Alt_L: special = GLUT_KEY_ALT_L; break;
+ case XK_Alt_R: special = GLUT_KEY_ALT_R; break;