function click(){
  if (event.button==2||event.button==3) {
     oncontextmenu='return false';
  }
}

function disableselect(e){
  return false;
}

function reEnable(){
  return true;
}

document.onmousedown = click
document.oncontextmenu = new Function("return false")

if (window.sidebar){
  document.onmousedown = disableselect
  document.onclick = reEnable
}