Changing the colour of the selection in GtkTreeView

[Geoff Bache <geoff carmen se>]

(I'm actually using PyGTK2, but nobody on that list knew the answer to 
this question and it was suggested that I try here).

I have a GtkTreeView, created in a fairly standard way. The thing is, I am 
using the background colour of the rows to display information to the 
user. It is then somewhat annoying when the user selects a row, which 
promptly turns dark blue, hiding the relevant information.

I would like to change the selection display to be indicated by a thin 
frame so that the original colour can still be seen. Does anyone know how 
I do this? I have tried editing the style of the TreeView itself, but that 
only seems to affect the display of the arrows at the left of the display.
The columns, it seems, are displayed by CellRendererText, but that isn't a 
Widget and hence doesn't have an associated Style. It does have a 
"background" property but it doesn't seem to depend on the state.

Regards,
Geoff Bache