How can I make my Firefox extension toolbar button appear automatically?

I've created a firefox extension that consists of a toolbar button. How can I set it up so that when my extension is installed, the button automatically appears in the main toolbar. I don't want my users to have to go to the customize toolbar menu and drag my button over.

From stackoverflow

• See https://developer.mozilla.org/En/Code_snippets:Toolbar#Adding_button_by_default

• May not be a good idea, the user may not want the extension to "congigure" his browser.

  I really hate things messing with my presets.

• We're using the following code....

  function init() {
  
      // .... 
  
      var navbar = document.getElementById("nav-bar");
      if ((myExtensionShared.checkMyBtnInstalled() == false) &&
          (navbar != null && document.getElementById("myExtension-button") == null)) {
          var newset;
              if (navbar.getAttribute('currentset') && 
                navbar.getAttribute('currentset').indexOf('myExtension-button') == -1) {
  
                  navbar.insertItem ('myExtension-button', null, null, false);
                  newset = navbar.getAttribute('currentset') + ',myExtension-button';
                  navbar.setAttribute('currentset', newset);
                  document.persist('nav-bar', 'currentset');
              }
              else if (!navbar.getAttribute('currentset')) {
  
                  navbar.insertItem ('myExtension-button', null, null, false);
                  newset=navbar.getAttribute('defaultset') + ',myExtension-button';
                  navbar.setAttribute('currentset', newset);
                  document.persist('nav-bar', 'currentset');
              }
  
      }
  
      // .... 
  
  }
  
  
  
  myExtensionShared.prototype.checkMyBtnInstalled = function() {
      var prefs = Components.classes["@mozilla.org/preferences-service;1"]
                                      .getService(Components.interfaces.nsIPrefBranch);
      var btnInstalled = false;
      if (prefs.prefHasUserValue("extensions.myExtension.myBtnInstalled")) {
          btnInstalled = prefs.getBoolPref("extensions.myExtension.myBtnInstalled");
      }
      if (!btnInstalled) {
          prefs.setBoolPref("extensions.myExtension.myBtnInstalled", true);
      }
      return btnInstalled;
  }
  

• We are using the following code that will append the button (if already exist somewhere else in the bar).

  //...
  appendButtonInToolbar:function(buttonId, toolbarId) {
      var toolbar = document.getElementById(toolbarId);
      var button = document.getElementById(buttonId);
      if(button) {
          var parentBar = button.parentNode;        
          if(parentBar && parentBar != toolbar) {
              var newset = this.removeButtonFromToolbarCurrentSet(parentBar,buttonId);              
          }
          toolbar.appendChild(button);
      }else{          
          toolbar.insertItem(buttonId);
      }
  
      this.appendButtonInToolbarCurrentSet(toolbar,buttonId);
  },
  
  appendButtonInToolbarCurrentSet:function(toolbar, buttonId) {
      var oldset = toolbar.getAttribute("currentset");
      var newset = "";
      if(oldset && oldset!="") {
          newset = oldset + ",";
      }        
      newset += buttonId;        
      toolbar.setAttribute("currentset", newset);
      document.persist(toolbar.id,"currentset");
      return newset;
  },
  
  
  removeButtonFromToolbarCurrentSet:function(toolbar, buttonId) {
      var oldset = toolbar.getAttribute("currentset");
      if(!oldset || oldset=="" || oldset.indexOf(buttonId) == -1) return oldset;
      var reg = new RegExp(buttonId+",?", "gi");        
      var newset = oldset.replace(reg,"");
      if (newset.charAt(newset.length-1) == ",") {
         newset = newset.substring(0, newset.length - 1);
      }
  
      toolbar.setAttribute("currentset", newset);
      document.persist(toolbar.id,"currentset");
      return newset;
  }, 
  //...