old_contents: {
      let util = {};
      Components.utils.import("resource://gipsy/util.jsm", util);
  
      let myId    = "gipsy-button"; // ID of button to add
      let afterId = "search-container";    // ID of element to insert after
      let navBar  = document.getElementById("nav-bar");
  
      if (navBar && !util.get_bool_pref('btn_toolbar_added')) {
          let curSet  = navBar.currentSet.split(",");
          if (curSet.indexOf(myId) == -1) {
              let pos = curSet.indexOf(afterId) + 1 || curSet.length;
              let set = curSet.slice(0, pos).concat(myId).concat(curSet.slice(pos));
  
              navBar.setAttribute("currentset", set.join(","));
              navBar.currentSet = set.join(",");
              document.persist(navBar.id, "currentset");
              try {
                  BrowserToolboxCustomizeDone(true);
              } catch (e) {}
              util.set_bool_pref('btn_toolbar_added', true);
          }
      }
  }
  
new_contents: {
      let GipsyUtil = {};
      Components.utils.import("resource://gipsy/util.jsm", GipsyUtil);
  
      let myId    = "gipsy-button"; // ID of button to add
      let afterId = "search-container";    // ID of element to insert after
      let navBar  = document.getElementById("nav-bar");
  
      if (navBar && !GipsyUtil.get_bool_pref('btn_toolbar_added')) {
          let curSet  = navBar.currentSet.split(",");
          if (curSet.indexOf(myId) == -1) {
              let pos = curSet.indexOf(afterId) + 1 || curSet.length;
              let set = curSet.slice(0, pos).concat(myId).concat(curSet.slice(pos));
  
              navBar.setAttribute("currentset", set.join(","));
              navBar.currentSet = set.join(",");
              document.persist(navBar.id, "currentset");
              try {
                  BrowserToolboxCustomizeDone(true);
              } catch (e) {}
              GipsyUtil.set_bool_pref('btn_toolbar_added', true);
          }
      }
  }
  
subject: Rename 'util' to 'GipsyUtil' in overlay.