function Picker1_onSelectionChanged(sender, eventArgs)
{
    Calendar1.setSelectedDate( Picker1.getSelectedDate() );
    updateHiddenFields();
}

function Calendar1_onSelectionChanged(sender, eventArgs)
{
    Picker1.setSelectedDate( Calendar1.getSelectedDate() );
    updateHiddenFields();
}

function Picker2_onSelectionChanged(sender, eventArgs)
{
    Calendar2.setSelectedDate( Picker2.getSelectedDate() );
    updateHiddenFields();
}

function Calendar2_onSelectionChanged(sender, eventArgs)
{
    Picker2.setSelectedDate( Calendar2.getSelectedDate() );
    updateHiddenFields();
}

function updateHiddenFields()
{
    document.getElementById("DateStartHidden").value = Calendar1.formatDate( Calendar1.getSelectedDate(), "yyyy-MM-dd" );
    document.getElementById("DateEndHidden").value   = Calendar2.formatDate( Calendar2.getSelectedDate(), "yyyy-MM-dd" );
}

function Button_OnClick(alignElement, calendar)
{
  if (calendar.get_popUpShowing())
  {
    calendar.hide();
  }
  else
  {
    calendar.show(alignElement);
  }
}

function Button_OnMouseUp(calendar, event)
{
  if (calendar.get_popUpShowing())
  {
    event.cancelBubble=true;
    event.returnValue=false;
    return false;
  }
  else
  {
    return true;
  }
}