Open the clock, click "Edit" Locations, click "Add", click "Find". The dialog is way too small, given the hugeness of the dataset it's searching through. (Eg, if you search for "Springfield", you're going to need a bunch of lines of context around it to be able to figure out if it's found the right Springfield.) (In the interest of not filing 7000 separate minor intlclock bugs, I'm going to also point out here that Esc fails to activate the "Cancel" button in both the "Add" dialog and the "Find" dialog)
Should be fixed, both upstream and in rawhide.