GtkSurfaces

#include <gtk/gtk.h>

GtkWidget *window, *child, *subchild;

#define EXAMPLE_FIXED_TYPE (example_fixed_get_type())
G_DECLARE_FINAL_TYPE(ExampleFixed, example_fixed, Example, Fixed, GtkFixed)

#define EXAMPLE_BOX_TYPE (example_box_get_type())
G_DECLARE_FINAL_TYPE(ExampleBox, example_box, Example, Box, GtkBox)

struct _ExampleFixed
{
    GtkFixed parent;
};

struct _ExampleBox
{
    GtkBox parent;
};

G_DEFINE_TYPE(ExampleFixed, example_fixed, GTK_TYPE_FIXED);
G_DEFINE_TYPE(ExampleBox, example_box, GTK_TYPE_BOX);

static void example_fixed_init(ExampleFixed *fixed)
{
    gtk_widget_set_has_surface (GTK_WIDGET (fixed), TRUE);
}

static void example_box_init(ExampleBox *box)
{
    gtk_widget_set_has_surface (GTK_WIDGET (box), TRUE);
}

static void example_fixed_realize(GtkWidget *widget)
{
    const GtkAllocation allocation;
    GdkSurface *surface, *fixedsurf;

    surface = gtk_widget_get_surface(window);
    fixedsurf = gdk_surface_new_child(surface, &allocation);
    gtk_widget_set_surface(widget, fixedsurf);
    gtk_widget_register_surface(widget, fixedsurf);
    GTK_WIDGET_CLASS(example_fixed_parent_class)->realize(widget);
}

static void example_box_realize(GtkWidget *widget)
{
    const GtkAllocation allocation;
    GdkSurface *surface, *boxsurf;

    surface = gtk_widget_get_surface(window);
    boxsurf = gdk_surface_new_child(surface, &allocation);
    gtk_widget_set_surface(widget, boxsurf);
    gtk_widget_register_surface(widget, boxsurf);
    GTK_WIDGET_CLASS(example_box_parent_class)->realize(widget);
}


static void example_fixed_class_init(ExampleFixedClass *klass)
{
    GtkWidgetClass *widget_class = GTK_WIDGET_CLASS(klass);
    widget_class->realize = example_fixed_realize;
}

static void example_box_class_init(ExampleBoxClass *klass)
{
    GtkWidgetClass *widget_class = GTK_WIDGET_CLASS(klass);
    widget_class->realize = example_box_realize;
}

GtkWidget *example_fixed_new()
{
    return g_object_new(EXAMPLE_FIXED_TYPE, NULL);
}

GtkWidget *example_box_new()
{
    return g_object_new(EXAMPLE_BOX_TYPE, NULL);
}

static void activate (GtkApplication* app, gpointer user_data)
{
  window = gtk_application_window_new (app);
  gtk_window_set_title (GTK_WINDOW (window), "Window");
  gtk_window_set_default_size (GTK_WINDOW (window), 1024, 768);
  child = example_fixed_new();
  subchild = example_box_new();
  gtk_container_add(GTK_CONTAINER(child), subchild);
  gtk_container_add(GTK_CONTAINER(window), child);
  gtk_widget_show (window);
}

int main (int argc, char **argv)
{
  GtkApplication *app;
  int status;

  app = gtk_application_new ("org.gtk.example", G_APPLICATION_FLAGS_NONE);
  g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
  status = g_application_run (G_APPLICATION (app), argc, argv);
  g_object_unref (app);

  return status;
}