moved includes related to GL to a separate header

glincludes.h

+#ifndef GLINCLUDES_H
+#define GLINCLUDES_H
+
+// GLew might not be needed on mac, or if a recent version of OpenGL is present
+#ifndef __APPLE__
+  #include <GL/glew.h>
+  #if (!defined GLEW_VERSION_1_5) || (!defined GL_VERSION_3_1)
+    #error GLEW 1.5.2 is required
+  #endif
+#endif
+
+#define GL_GLEXT_PROTOTYPES 1
+#ifdef __APPLE__
+  #include<OpenGL/gl.h>
+  #include<OpenGL/glu.h>
+  #include<Glut/glut.h>
+  #include<OpenGL/glext.h>
+#else
+  //#include <GL/gl.h>
+  //#include <GL/glu.h>
+  #include <GL/glut.h>
+  // is glext really needed?
+  //#include <GL/glext.h>
+#endif
+
+#endif // GLINCLUDES_H

openglcanvas.h

 #ifndef OPENGLCANVAS_H
 #define OPENGLCANVAS_H
 
-// GLew might not be needed on mac, or if a recent version of OpenGL is present
-#ifndef __APPLE__
-  #include <GL/glew.h>
-  #if (!defined GLEW_VERSION_1_5) || (!defined GL_VERSION_3_1)
-    #error GLEW 1.5.2 is required
-  #endif
-#endif
-
-#define GL_GLEXT_PROTOTYPES 1
-#ifdef __APPLE__
-  #include<OpenGL/gl.h>
-  #include<OpenGL/glu.h>
-  #include<Glut/glut.h>
-  #include<OpenGL/glext.h>
-#else
-  //#include <GL/gl.h>
-  //#include <GL/glu.h>
-  #include <GL/glut.h>
-  // is glext really needed?
-  //#include <GL/glext.h>
-#endif
-
+#include "glincludes.h"
 #include <QGLWidget>
 #include <QTimer>
 #include <QFile>