Pavel,
I have tried to contact Dave but with no luck. I am struggling with tessellation under windows where it is not working for me at all. Under linux it is fine.

I think there may be something re-writting the screen, but not calling the plugin RenderGLOverlay so that my filled boundaries are not redrawn. At times the boundary points flicker, the rollover popup seems to work only intermittently, and under VirtualBox where I run Win 7 for testing it is VERY sensitive to what I can do with the glu stuff. If I set glPolygonMod to GL_LINE and gluTessProperty GLU_TESS_BOUNDARY_ONLY to GL_TRUE, most of the charts stop rendering. That suggests that somewhere the setup is not being done correctly and that assumptions are being made. I think my plugin may now be breaking these assumptions. I posted an example up on the OCPN-Draw and Boundary stream on the forum, post #179.

Any help you or Dave can give would be great.

Thanks
Jon