code: public static void registerTipLayout (String prefix, TipLayout layout)
      {
          LayoutReg reg = new LayoutReg();
          reg.prefix = prefix;
          reg.layout = layout;
          _layouts.insertSorted(reg);
      }
docs: It may be desirable to layout object tips specially depending on
  what sort of actions they represent, so we allow different tip
  layout algorithms to be registered for particular object prefixes.
  The registration is simply a list searched from longest string to
  shortest string for the first match to an object's action.