It works! Eureka!

gdk/gdkpixmap.c

@@ -336,9 +336,16 @@ gdk_pixmap_real_get_visual (GdkDrawable *drawable)
 static gint
 gdk_pixmap_real_get_depth (GdkDrawable *drawable)
 {
+  gint depth;
+  
   g_return_val_if_fail (GDK_IS_PIXMAP (drawable), 0);
 
-  return ((GdkPixmapObject *)drawable)->depth;
+  depth = ((GdkPixmapObject *)GDK_PIXMAP (drawable))->depth;
+
+  if (depth == 0)
+    g_print ("0 depth for type %s\n", g_type_name (G_OBJECT_TYPE (drawable)));
+
+  return depth;
 }
 
 static void

gdk/gdkwindow.c

@@ -1297,9 +1297,19 @@ gdk_window_real_get_visual (GdkDrawable *drawable)
 static gint
 gdk_window_real_get_depth (GdkDrawable *drawable)
 {
+  gint depth;
+  
   g_return_val_if_fail (GDK_IS_WINDOW (drawable), 0);
 
-  return ((GdkWindowObject *)drawable)->depth;
+  depth = ((GdkWindowObject *)GDK_WINDOW (drawable))->depth;
+
+  if (depth == 0)
+    {
+      g_print ("0 depth for type %s\n", g_type_name (G_OBJECT_TYPE (drawable)));
+      G_BREAKPOINT ();
+    }
+
+  return depth;
 }
 
 static void
@@ -1477,7 +1487,7 @@ gdk_window_invalidate_rect   (GdkWindow    *window,
 	  GdkWindowObject *child = tmp_list->data;
 	  tmp_list = tmp_list->next;
 
-	  if (((GdkWindowObject *)child)->input_only)
+	  if (!((GdkWindowObject *)GDK_WINDOW (child))->input_only)
 	    {
               gint width, height;
 

gdk/x11/gdkgeometry-x11.c

@@ -87,7 +87,8 @@ _gdk_windowing_window_get_offsets (GdkWindow *window,
 				   gint      *x_offset,
 				   gint      *y_offset)
 {
-  GdkWindowImpl *impl = GDK_WINDOW_IMPL (((GdkWindowObject *) window)->impl);
+  GdkWindowImpl *impl =
+    GDK_WINDOW_IMPL (((GdkWindowObject *) GDK_WINDOW (window))->impl);
 
   *x_offset = impl->position_info.x_offset;
   *y_offset = impl->position_info.y_offset;
@@ -101,7 +102,8 @@ _gdk_window_init_position (GdkWindow *window)
   
   g_return_if_fail (GDK_IS_WINDOW (window));
 
-  impl = GDK_WINDOW_IMPL (((GdkWindowObject*)window)->impl);
+  impl =
+    GDK_WINDOW_IMPL (((GdkWindowObject*) GDK_WINDOW (window))->impl);
   
   gdk_window_compute_parent_pos (impl, &parent_pos);
   gdk_window_compute_position (impl, &parent_pos, &impl->position_info);
@@ -128,8 +130,8 @@ _gdk_window_move_resize_child (GdkWindow *window,
   g_return_if_fail (window != NULL);
   g_return_if_fail (GDK_IS_WINDOW (window));
 
-  impl = GDK_WINDOW_IMPL (((GdkWindowObject *) window)->impl);
-  obj = (GdkWindowObject *) window;
+  impl = GDK_WINDOW_IMPL (((GdkWindowObject *) GDK_WINDOW (window))->impl);
+  obj = (GdkWindowObject *) GDK_WINDOW (window);
   
   dx = x - obj->x;
   dy = y - obj->y;
@@ -279,7 +281,8 @@ gdk_window_compute_position (GdkWindowImpl      *window,
 
   g_return_if_fail (GDK_IS_WINDOW_IMPL (window));
 
-  wrapper = (GdkWindowObject *) GDK_DRAWABLE_IMPL (window)->wrapper;
+  wrapper =
+    (GdkWindowObject *) GDK_WINDOW (GDK_DRAWABLE_IMPL (window)->wrapper);
   
   info->big = FALSE;
   
@@ -379,7 +382,8 @@ gdk_window_compute_parent_pos (GdkWindowImpl      *window,
 
   g_return_if_fail (GDK_IS_WINDOW_IMPL (window));
 
-  wrapper = (GdkWindowObject *)GDK_DRAWABLE_IMPL (window)->wrapper;
+  wrapper =
+    (GdkWindowObject *) GDK_WINDOW (GDK_DRAWABLE_IMPL (window)->wrapper);
   
   parent_pos->x = 0;
   parent_pos->y = 0;
@@ -416,8 +420,8 @@ gdk_window_compute_parent_pos (GdkWindowImpl      *window,
 
       parent_pos->x += parent->x;
       parent_pos->y += parent->y;
-      parent_pos->x11_x += window->position_info.x;
-      parent_pos->x11_y += window->position_info.y;
+      parent_pos->x11_x += impl->position_info.x;
+      parent_pos->x11_y += impl->position_info.y;
 
       clip_xoffset += parent->x;
       clip_yoffset += parent->y;

gdk/x11/gdkwindow-x11.c

@@ -449,6 +449,7 @@ gdk_window_new (GdkWindow     *parent,
   else
     {
       depth = 0;
+      private->depth = 0;
       class = InputOnly;
       private->input_only = TRUE;
       draw_impl->colormap = NULL;