public function UninstallDependency($Alias, $PropertyName = NULL) {
      if(array_key_exists($Alias, $this->_Dependencies)) {
         if(is_null($PropertyName))
            unset($this->_Dependencies[$Alias]);
         elseif(array_key_exists($PropertyName, $this->_Dependencies[$Alias]))
               unset($this->_Dependencies[$Alias][$PropertyName]);
      }
   }