//////// SUBMENU HANDLING ////////
// ds: toggleMenu ( 'id' )
//     used to open en close the submenu's
function toggleMenu(id) {
  if ( document.openMenu != id ) {
    //close the already open menu
    if (document.openMenu) {
      setStyle(document.openMenu, 'display', 'none');
    }
    // open clicked submenu
    setStyle(id, 'display', 'block');
    document.openMenu = id;
  } else {
    // close clicked submenu
    setStyle(id, 'display', 'none');
    document.openMenu = null;
  }
}

// ds: getStyle ( 'elementName', 'style' )
//     used to get the value of a style element
function getStyle(obj, style) {
  // get the value to the element
  return document.getElementById(obj).style[style];
}


// ds: setStyle ( 'elementName', 'style', 'value' )
//     used to set the value of a style element
function setStyle(obj, style, value) {
  // set the new value to the element
  document.getElementById(obj).style[style] = value;
}


// ds: setClass ( 'elementName', 'value' )
//     used to assign a class to a style element
function setClass(obj, value) {
  // set the new value to the element
  document.getElementById(obj).className = value;
}