var TimeOut          = 300;
var currentLayer     = null;
var currentLayerMenu = null;
var closeTimer       = null;

// ドロップメニューを開く
function OpenDrop(n) {

  var l  = document.getElementById(n);

  if(l) {
    CancelClose();
    l.style.visibility='visible';
    if(currentLayer && (currentLayerMenu != n))
      currentLayer.style.visibility='hidden';
    currentLayer = l;
    currentLayerMenu = n;
  }
  else if(currentLayer) {
    CancelClose();
    currentLayer.style.visibility='hidden';
    currentLayerMenu = null;
    currentLayer = null;
  }
}


// ドロップメニューをからフォーカス外れた
function CloseTimer() {
  closeTimer = window.setTimeout(CloseMenu, TimeOut);
}

function CancelClose() {
  if(closeTimer) {
    window.clearTimeout(closeTimer);
    closeTimer = null;
  }
}

function CloseMenu() {
  if(currentLayer) {
    currentLayer.style.visibility='hidden';
    currentLayerMenu = null;
    currentLayer = null;
  }
  currentLayer = null;
}