var currentOpenMenu = -1;
function ShowMenu(id)
{
    if ( currentOpenMenu !== -1 )
        document.getElementById('menu'+currentOpenMenu).style.display = 'none';
    if ( id != currentOpenMenu ) {
        document.getElementById('menu'+id).style.display = 'inline';
        currentOpenMenu = id;
    } else
        currentOpenMenu = -1;
}