Problem concerning OpenGL + SDL

#include <SDL/SDL.h>#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <GL/gl.h>#include <GL/glu.h>#define TRUE  1#define FALSE 0int init_GL( GLvoid ){	// Enable smooth shading 	glShadeModel( GL_SMOOTH );	// Set the background black 	glClearColor( 0.0f, 0.0f, 0.0f, 0.0f );	// Depth buffer setup 	glClearDepth( 1.0f );	// Enables Depth Testing	glEnable( GL_DEPTH_TEST );	// The Type Of Depth Test To Do	glDepthFunc( GL_LEQUAL );	// Really Nice Perspective Calculations	glHint( GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST );	return 1;}int draw_GL(GLvoid)                // Here's Where We Do All The Drawing{		// These are to calculate our fps	static GLint T0     = 0;	static GLint Frames = 0;	// Clear The Screen And The Depth Buffer	glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );	// Move Left 1.5 Units And Into The Screen 6.0	glLoadIdentity();	glTranslatef( -1.5f, 0.0f, -6.0f );	glRotatef(50,0.0f,1.0f,0.0f);                         // Rotate The Pyramid On It's Y Axis	glBegin( GL_TRIANGLES );            // Drawing Using Triangles 	glColor3f(1.0f,0.0f,0.0f);                      // Red	glVertex3f( 0.0f, 1.0f, 0.0f);                  // Top Of Triangle (Front)	glColor3f(0.0f,1.0f,0.0f);                      // Green	glVertex3f(-1.0f,-1.0f, 1.0f);                  // Left Of Triangle (Front)	glColor3f(0.0f,0.0f,1.0f);                      // Blue	glVertex3f( 1.0f,-1.0f, 1.0f);                  // Right Of Triangle (Front)	glColor3f(1.0f,0.0f,0.0f);                      // Red	glVertex3f( 0.0f, 1.0f, 0.0f);                  // Top Of Triangle (Right)	glColor3f(0.0f,0.0f,1.0f);                      // Blue	glVertex3f( 1.0f,-1.0f, 1.0f);                  // Left Of Triangle (Right)	glColor3f(0.0f,1.0f,0.0f);                      // Green	glVertex3f( 1.0f,-1.0f, -1.0f);                 // Right Of Triangle (Right)	glColor3f(1.0f,0.0f,0.0f);                      // Red	glVertex3f( 0.0f, 1.0f, 0.0f);                  // Top Of Triangle (Back)	glColor3f(0.0f,1.0f,0.0f);                      // Green	glVertex3f( 1.0f,-1.0f, -1.0f);                 // Left Of Triangle (Back)	glColor3f(0.0f,0.0f,1.0f);                      // Blue	glVertex3f(-1.0f,-1.0f, -1.0f);                 // Right Of Triangle (Back)	glColor3f(1.0f,0.0f,0.0f);                      // Red	glVertex3f( 0.0f, 1.0f, 0.0f);                  // Top Of Triangle (Left)	glColor3f(0.0f,0.0f,1.0f);                      // Blue	glVertex3f(-1.0f,-1.0f,-1.0f);                  // Left Of Triangle (Left)	glColor3f(0.0f,1.0f,0.0f);                      // Green	glVertex3f(-1.0f,-1.0f, 1.0f);                  // Right Of Triangle (Left)    glEnd( );                           // Finished Drawing The Triangle    // Move Right 3 Units    glTranslatef( 3.0f, 0.0f, 0.0f );    glBegin( GL_QUADS );                // Draw A Quad      glVertex3f( -1.0f,  1.0f, 0.0f );      glVertex3f(  1.0f,  1.0f, 0.0f );       glVertex3f(  1.0f, -1.0f, 0.0f );       glVertex3f( -1.0f, -1.0f, 0.0f );     glEnd( );                           // Done Drawing The Quad    /* Draw it to the screen */    SDL_GL_SwapBuffers( );    /* Gather our frames per second */    return( 1 );}int show_Window(GLvoid){	//Height / width ration 	GLfloat ratio;	// Protect against a divide by zero	ratio = ( GLfloat )1024 / ( GLfloat )768;	// Setup our viewport.	glViewport( 0, 0, ( GLsizei )1024, ( GLsizei )768 );	// change to the projection matrix and set our viewing volume. //	glMatrixMode( GL_PROJECTION );	glLoadIdentity( );	// Set our perspective	gluPerspective( 45.0f, ratio, 0.1f, 100.0f );	// Make sure we're chaning the model view and not the projection 	glMatrixMode( GL_MODELVIEW );	// Reset The View 	glLoadIdentity( );}int main (void) {		SDL_Surface *screen;	if (SDL_Init ( SDL_INIT_VIDEO ) != 0) {		printf ("Konnte SDL nicht initialisieren: %s\n",		SDL_GetError ());	return EXIT_FAILURE;	}	screen = SDL_SetVideoMode (1024, 768, 32,SDL_FULLSCREEN|SDL_OPENGL|SDL_HWPALETTE|SDL_GL_DOUBLEBUFFER);	if (screen == NULL) {	     printf ("Videomodus konnte nicht eingerichtet werden: "              " %s\n", SDL_GetError ());		return EXIT_FAILURE;	}	init_GL( );	show_Window( );	draw_GL( );	SDL_Delay (8000);	printf ("Erfolgreich beendet!\n");	//SDL_ListModes   return EXIT_SUCCESS;}