Works perfectly for me with Nautilus 2.16.1 on Ubuntu Edgy and I use this feature frequently. Can you make sure you have Gamin [1] installed and that it is working properly?

[1] http://www.gnome.org/~veillard/gamin/

Using Feisty here, with Nautilus 2.17.90. gamin works as it should. Note that the size updates with files, but doesn't with directories.

$ wget --mirror www.gnome.org
and look at the properties for ~/www.gnome.org/

Yes, it doesn't seem to work with folders. I can't test with 2.17.90 right now, but I'll take your word for it. Confirming.

Does this bug still exist in Nautilus as of the GIO refactoring?

Yes, it's the same as before in Nautilus 2.24.1. Works with files but not with folders.

Created attachment 223073 [details] [review]
Update directory size in properties when it changes

Review of attachment 223073 [details] [review]:

::: src/nautilus-properties-window.c
@@ +971,3 @@
 		}
+		if (changed_file != NULL) {
+			nautilus_file_recompute_deep_counts (changed_file);

I think this should go into the if (dirty_target) block below, since that's where we update all the other value fields from.

Review of attachment 223073 [details] [review]:

::: src/nautilus-properties-window.c
@@ +971,3 @@
 		}
+		if (changed_file != NULL) {
+			nautilus_file_recompute_deep_counts (changed_file);

And iterate over the files again? Not sure what the benefit is to be honest.

Review of attachment 223073 [details] [review]:

Yeah I was missing the fact that changed_file is just an iter over a list. Makes sense then.