(version 3)
<a id="home_link" rel="localize[masthd.home]" onclick="iLO.openLink("summary.html");this.blur();return false;" href="summary.html">Home</a>
  | 
<button id="logout_button" rel="localize[masthd.signout]" onclick="iLO.doLogout();">Sign Out</button>

##</code><code>##

(version 4)
<a id="home_link" rel="localize[masthd.home]" onclick="iLO.openLink("summary.html");this.blur();return false;" href="summary.html">Home</a>
  | 
<button id="logout_button" rel="localize[masthd.signout]" onmouseup="iLO.doLogout();">Sign Out</button>

##</code><code>##

$mech->click_button(id => 'logout_button');

##</code><code>##

(in cleanup) MozRepl::RemoteObject: ReferenceError: iLO is not defined at ...