Not sure how to apply, but i was looking at the highgui files and in modules/highgui/src/window_gtk.cpp if found:
#if (GTK_MAJOR_VERSION == 3) && defined(HAVE_OPENGL)
#undef HAVE_OPENGL // no support with GTK3
#endif
So does this mean that OpenGL and GTK 3 are not supported with OpenGL, and i should use GTK 2?