// this function is called when the user selects an action that should
// hide or unhide an element in the document/page.

function toggle_display ( targetId ) 
{
  // Taken from page 372 (chapter 15) of Designing with Web Standards
  if ( document.getElementById ) {
    target = document.getElementById ( targetId );
    if (target.style.display == "none") {
      target.style.display = "";
    } else {
      target.style.display = "none";
    }
  }
}