Getting GtkD working with OpenGL

[Chalix via Digitalmars-d-learn]

On Monday, 3 October 2016 at 18:00:53 UTC, Mike Wey wrote:
> The signal functions can be found in the gobject.Signals module.
>
> But you should use the GLArea.addOnCreateContext / addOnRender 
> / addOnResize functions to attach a D delegate to the signal.
> You will still need to link with the OpenGL libraries or use 
> someting like Derelict.

Hi Mike, thanks for your fast answer again!

I just read about this delegates and I liked the concept. I 
experimented with it for a while and read a bit on the Internet, 
but I still don't get it working...

My minimal example looks like this:

import gtk.Main;
import gtk.MainWindow;
import gtk.GLArea;
import glgdk.GLContext;

void main(string[] args)
{
	bool render(GLContext context, GLArea area)
	{
		return true;
	}

	Main.init(args);
	MainWindow win = new MainWindow("Hello World");
	GLArea area = new GLArea();

	area.addOnRender(&render,cast(GConnectFlags)0);

	win.add(area);
	win.showAll();
	Main.run();
}

If I compile it, I get this error:

$ dmd main.d -I/usr/local/include/d/gtkd-3 -L-lgtkd-3
main.d(27):
Error: function gtk.GLArea.GLArea.addOnRender
(bool delegate(GLContext, GLArea) dlg, GConnectFlags connectFlags 
= cast(GConnectFlags)0)
is not callable using argument types
(bool delegate(GLContext context, GLArea area), GConnectFlags)

I cant see, what I am doing wrong... Someone else sees the error? 
Tomorrow I try to subclass the GLArea, if this works I am happy 
:) But I'd like to use the handler stuff.

Ah, and I know now, that I have to link against the GL and GLU 
library, but which module do I have to import, to make the 
functions visible for the compiler? Or do I need another binding 
therefore?