(Gtk bug?)

If for example you're entering the pathname of an icon
for a launcher on the GNOME panel (or indeed entering text
in any Gtk text field with a history dropdown, it seems),
it remembers any old entries in the history dropdown.  This
is great, but there are two bugs:

   + it doesn't remove duplicates from the history dropdown
   + if there is an entry in the history dropdown which
     matches the one you are trying to enter, ignoring
     differences in case, it auto-corrects your entries
     capitalization to that of the one in the history.
     This is very nice except for one problem: if you
got         the capitalization wrong first time, you're then
sunk        -- you can't enter it the right way!