Becero, schifoso, ma funzionante:
codice:
...
...
function depressButton(button) {

  var x, y;

  // Update the button's style class to make it look like it's
  // depressed.

  button.className += " menuButtonActive";

  // Position the associated drop down menu under the button and
  // show it.

  x = getPageOffsetLeft(button);
  y = getPageOffsetTop(button) + button.offsetHeight;

  button.menu.style.left = "8px";  //x + "px";
  button.menu.style.top  = y + "px";
  button.menu.style.visibility = "visible";
}
...
...
HTH
Zappa