window.addLoadEvent = function(func) {
   var oldonload = window.onload;
   if (typeof window.onload != 'function') {
      window.onload = func;
   } else {
      window.onload = function() {
         if (oldonload) 
            oldonload();
         func();
      }
   }
};

window.addUnloadEvent = function(func) {
   var oldonunload = window.onunload;
   if (typeof window.onunload != 'function') {
      window.onunload = func;
   } else {
      window.onunload = function() {
         if (oldonunload) 
            oldonunload();
         func();
      }
   }
};

window.addSubmitEvent = function(form, func) {
   var oldonsubmit = form.onsubmit;
   if (typeof oldonsubmit != 'function') {
      form.onsubmit = func;
   } else {
      form.onsubmit = function() {
         var returnVal;
         
         if (oldonsubmit) 
            returnVal = oldonsubmit();
         
         func();
         
         return returnVal;
      }
   }
};