I have some code for this at home, but I failed when trying to draw reasonably-looking 
south-west corner resize grips...
One nasty gotcha with this is that you will run 
into assertions from 
theme engines when gtk starts drawing resize grips in corners 
other than south-east, since there typically is a switch with default: 
g_assert_not_reached()...so all theme engines will need an update when this is 
done.

Here is the flipping code for status bars. It needs on the patches
attached to 52833, otherwise you'll run into g_assert_not_reached ().

Created attachment 11891 [details] [review]
patch

The asymetry in dealing with GTK_CONTAINER (widget)->border_width in:

+  if (gtk_widget_get_direction (widget) == GTK_TEXT_DIR_LTR) 
+    {
+      rect->x = widget->allocation.x + widget->allocation.width - w;
+      edge = GDK_WINDOW_EDGE_SOUTH_EAST; 
+    }
+  else 
+    {
+      rect->x = widget->allocation.x + GTK_CONTAINER
(widget)->border_width +
+	widget->style->xthickness;
+      edge = GDK_WINDOW_EDGE_SOUTH_WEST; 
+    }

looks suspicious to me. 

Wouldn't it be better to have a get_grip_edge() function rather
than pushing it in as the return value here and computing it
separately elsewhere?

You're right. Looks suspicious. Here is a new patch which simply
removes the border_width and adds a separate get_grip_edge(). The grip
on the left is still not looking perfect, due to the heavy dark bevel
next to it (see below). Not sure if we can do anything about it.
Looking at IE, the resize grips on Windows seem to be drawn over the
bevel, rather than
inside it.

Created attachment 11976 [details] [review]
revised patch

Created attachment 11977 [details]
a flipped statusbar

Hey Owen, any chance to look at the revised patch ?

I'm still striving for an almost 
complete rtl support in 2.2...

Looks fine. Not sure if anything can be done about the
drawing. 

Committed to HEAD.