When start network load, disable menu item nav-menu-button, enables stop. And the treatment the other way around.

minimo/chrome/content/minimo.js

@@ -103,6 +103,10 @@ nsBrowserStatusHandler.prototype =
       
       if (aStateFlags & nsIWebProgressListener.STATE_START)
       {
+        // disable and hides the nav-menu-button; and enables unhide the stop button
+		document.getElementById("nav-menu-button").hidden=true;
+		document.getElementById("nav-stop-button").hidden=false;
+
         // Notify anyone interested that we are loading.
         try {
           var os = Components.classes["@mozilla.org/observer-service;1"]
@@ -131,6 +135,10 @@ nsBrowserStatusHandler.prototype =
             if (aWebProgress.DOMWindow == content) this.endDocumentLoad(aRequest, aStatus);
         }
 
+        // disable and hides the nav-stop-button; and enables unhides the nav-menu-button button
+		document.getElementById("nav-menu-button").hidden=true;
+		document.getElementById("nav-stop-button").hidden=false;
+
         return;
       }
       return;