My minimal working code gtkd/gl

import gtk.Main;
import gdk.GLContext;
import gtk.GLArea;
import gtk.MainWindow;
import gtk.Widget;

import derelict.opengl3.gl3;

class MyArea : GLArea {
    bool render (GLContext c, GLArea a)
    {
        makeCurrent();
        glClearColor(1,0,0,1);
        glClear(GL_COLOR_BUFFER_BIT);
        return true;
    }
}
class ExampleWindow : MainWindow
{
    this()
    {
        super("GtkD: Try");

        MyArea glarea = new MyArea();
        glarea.addOnRender(&glarea.render);
        add(glarea);
        showAll();
    }
}

void main(string[] arg)
{
    DerelictGL3.load();
    Main.init(arg);
    new ExampleWindow();
    Main.run();
}