it's getting warmer, window doesnt freeze anymore and opengl calls don't crash the window, but it's still all white after calling glClearColor(1,0,1,1); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); updated src: https://github.com/oggs91/OpenVG_D/blob/master/demo_DvisualizationWT/source/app.d