public void OnShow()
        {
            _contextPtr = OpenGl.GlXCreateContext(_window.NativeHandle, ref _visualInfo, IntPtr.Zero, true);
            OpenGl.GlXMakeCurrent(_window.NativeHandle, _window.WindowId, _contextPtr);

            WindowExtensions.LoadDefaultOpenGLFunctions();
        }
        public void OnShow()
        {
            MakeContextCurrent();

            WindowExtensions.LoadDefaultOpenGLFunctions();
        }