var erased = false;
var defaultValue = '';

function clear_input(element)
{
  element.value = '';
  erased = true;
}

Event.observe(window, 'load', function() {
  defaultValue = $('hotel_ou_ville').value;
  $('errorMessage').observe('click', function () {
    $('errorMessage').hide();
  });
  $('bookingEngine').observe('submit', function()
  {
    if (defaultValue == $F('hotel_ou_ville'))
    {
      clear_input($('hotel_ou_ville'));
    }
  });
  $('hotel_ou_ville').observe('focus', function()
  {
    if(!erased)
	{
	  clear_input($('hotel_ou_ville'));
	}
  });
});