title: Gtkmm ListStore, how to catch that value in one of the rows was changed?
body: <p>I need to redraw image when some value in table will change. I want to know how to catch a changing of values in table.
  I found signal_row_changed, but it give const Gtk::TreeModel::Path&amp; and const Gdk::TreeModel::iterator&amp;.
  And when I do something like this:</p>
  
  <pre><code>...
  void PrMainWindow::redraw(){...}
  ...
  nRefTree-&gt;signal_row_changed().connect
      (sigc::mem_fun(*this,
                    &amp;PrMainWindow::redraw));
  </code></pre>
  
  <p>where nRefTree - Glib::Refptr, compiler give me the error.
  But, if I do</p>
  
  <pre><code>void PrMainWindow::redraw(
      const Gtk::TreeModel::Path&amp; path,
      const Gtk::TreeModel::iterator&amp; iter)
  {...}
  </code></pre>
  
  <p>than it works, but I don't need these references because this function can be called from other places and without these parameters.</p>
  
  <p>Maybe there is some other signal for this or method for cutting useless parameters? Help, please.</p>