Please describe the problem:
When the Open With properties tab has multiple entries, clicking on the radio gadgets to select one as the default does not change anything.

Steps to reproduce:
1. Create a text file on your desktop
2. Right click on it and choose Properties
3. Go to the Open With tab and ensure there are multiple entries (add some more if only Text Editor is there - e.g. add GVim)
4. Try to change the default


Actual results:
The default does not change

Expected results:
The default should change

Does this happen every time?
Yes

Other information:
Tested on two Ubuntu Hardy (8.04) machines, one a fresh install, the other an upgrade from Gutsy (7.10).
Also tested on a fresh Gutsy install and it works as expected, so it seems to be a regression.