[retro-gtk/wip/aplazas/display-for-filter] hack: Override RetroGlDisplay (un)realize and draw

[Adrien Plazas <aplazas src gnome org>]

commit 8e78ef4fcd031794b24a99a727bb0c94180919ae
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Fri Mar 23 10:44:15 2018 +0100

    hack: Override RetroGlDisplay (un)realize and draw

 retro-gtk/retro-gl-display.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
---
diff --git a/retro-gtk/retro-gl-display.c b/retro-gtk/retro-gl-display.c
index a4547c0..f207272 100644
--- a/retro-gtk/retro-gl-display.c
+++ b/retro-gtk/retro-gl-display.c
@@ -367,12 +367,32 @@ retro_gl_display_finalize (GObject *object)
   G_OBJECT_CLASS (retro_gl_display_parent_class)->finalize (object);
 }
 
+static void
+realize (GtkWidget *widget) {
+}
+
+static void
+unrealize (GtkWidget *widget) {
+}
+
+static gboolean
+draw (GtkWidget *widget,
+      cairo_t   *cr)
+{
+  return TRUE;
+}
+
 static void
 retro_gl_display_class_init (RetroGLDisplayClass *klass)
 {
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
 
   object_class->finalize = retro_gl_display_finalize;
+
+  widget_class->realize = realize;
+  widget_class->unrealize = unrealize;
+  widget_class->draw = draw;
 }
 
 static void