Comment 3 for bug 579134

Could someone test if something like the attached patch will work?

In order to test it you have to
  * apply the patch
  * go to po/ directory
  * run `intltool-update es` (update the Spanish translation adding new translatabe strings)
  * edit es.po translating "%l:%M %p" as "%k:%M"
  * run make && make install
  * logout and login using Spanish as session language.

However, here[1] is the snipped from gnome-panel used to update the date/time label.

http://git.gnome.org/browse/gnome-panel/tree/applets/clock/clock.c#n428