function showHideBtn(elementId, buttonId, buttonId3)
{
    var element = document.getElementById(elementId);
    var button = document.getElementById(buttonId);
    var button3 = document.getElementById(buttonId3);

    if (element == null || button == null)
        return;
    if (element.style.display == "none")
    {
        element.style.display = "block";
        button.value = "«";
      if ( button3 != null ) {
        button3.value = "»";
         }
        return;
    }
    element.style.display = "none";
    button.value = "»";
    if ( button3 != null ) {
    button3.value = "«";
    }
}