WindowsForm Appliction and GLControl questions.

1 and 2 - nothing comes to mind.

3 - yes. Some functionality is only available if you derive from GLControl. This includes support for OpenGL 3.0, custom pixel formats and the RecreateHandle() method (which can be useful in some uncommon scenarios).

4 - absolutely.

5 - there's no need to p/invoke platform-specific functions. OpenTK hides all platform-specific functionality behind cross-platform interfaces: DisplayResolution, GraphicsMode and GraphicsContext. These provide everything you need to emulate NeHe, like setting a display mode, selecting a pixel format and creating the OpenGL context (the latter is handled automatically by GLControl).

Hints:

• As long as you avoid platform-specific code, you'll be able to copy & paste your project on MacOS or Linux and it will work out of the box (you won't even need to recompile).
• Add "OpenTK.dll.config" to your project and set it to be copied to the output directory (necessary for cross-platform support).
• Use the settings designer in Visual Studio to create application settings. You can create a settings GUI trivially by using a PropertyGrid and binding it to the Settings class.

No, it's nothing like that. You simply create a new class:

class CustomGLControl : GLControl
{
    // Request an OpenGL 3.0 context.
    public CustomGLControl()
        : base(GraphicsMode.Default, 3, 0, GraphicsContextFlags.Default)
    { }
}

Compile the project and this new class will appear in your toolbox - simply drag & drop it instead of a vanilla GLControl.

Edit: the reason for this is that the WinForms designer only uses parameterless constructors. The necessary functionality exists in GLControl, but you can only access it through code, not the designer.

Hm, maybe it needs to be public (rebuild the project afterwards). If it still doesn't appear, right click on the toolbox, select "choose items" and enable the new control there.