Comment 1 for bug 969050

Disabling _update_selected_row fixes it, so its something to do with that:

=== modified file 'softwarecenter/ui/gtk3/widgets/apptreeview.py'
--- softwarecenter/ui/gtk3/widgets/apptreeview.py 2012-03-30 07:26:46 +0000
+++ softwarecenter/ui/gtk3/widgets/apptreeview.py 2012-03-30 10:16:58 +0000
@@ -285,6 +296,7 @@
         self._update_selected_row(view, tr, path)

     def _update_selected_row(self, view, tr, path=None):
+ return
         # keep track of the currently selected row renderer and associated
         # doc for use when updating the widgets and for use with the Unity
         # integration feature