Minimal GTK custom widget implementation

ggtkwindow.c

#include "ggtkwindow.h"

// Define the structure of the type
struct _GGtkWindow
{
	GtkLayout parent_instance;
	
	// private data here
	// because this is a final type, I don't need to use G_DEFINE_TYPE_WITH_PRIVATE
	// and jump through all the hoops that entails. That is required
	// when this can be derivable, because otherwise changing private members
	// would affect the size of the struct (and hence ABI compatibility)
};

static void ggtk_window_class_init(GGtkWindowClass *a)
{
	// Used to initialise property getters/setters and virtual functions
	// https://developer.gnome.org/gobject/stable/howto-gobject-methods.html#virtual-public-methods
}

static void ggtk_window_init(GGtkWindow *a)
{
	// Used to perform initialisation of an instance of this object
}

GtkWidget* ggtk_window_new(void)
{
	return GTK_WIDGET(GGTK_WINDOW(g_object_new(GGTK_TYPE_WINDOW, NULL)));
}

G_DEFINE_TYPE(GGtkWindow, ggtk_window, GTK_TYPE_LAYOUT)

ggtkwindow.h

#include <gtk/gtk.h>

#ifndef __GGTK_WINDOW_H
#define _GGTK_WINDOW_H


#define GGTK_TYPE_WINDOW ggtk_window_get_type()
G_DECLARE_FINAL_TYPE(GGtkWindow, ggtk_window, GGTK, WINDOW, GtkLayout)

struct _GGtkWindowClass
{
	GtkLayoutClass parent_class;
	
	// virtual methods here, no pad because screw ABI compat, it's internal
};

#endif __GTTK_WINDOW_H