The current samples are not handling correctly the resizing of the window : <img width="1032" alt="Capture d’écran 2024-02-26 à 18 45 15" src="https://github.com/opentk/LearnOpenTK/assets/57635141/4708b7fc-85db-443c-affb-ba188a5c0151"> Current code : GL.Viewport(0, 0, Size.X, Size.Y); Proposal for fix : Vector2i fb = this.FramebufferSize; GL.Viewport(0, 0, fb.X, fb.Y);