I am working on a multi-page form filler to login to Yahoo Mail, but have run into a problem.

The code works when I run firefox in X11 with a display, but fails when I run firefox in Xvfb. Xvfb is setuid. I can watch it run in X11 with a display (which happens to be running on my mac - the server where fillform.pl runs is Debian Squeeze).

This is where the code fails in fillform.pl when I try to use Xvfb. I can see it connect to firefox from the MOZREPL log:

my $mech = WWW::Mechanize::Firefox->new() ;
print "debug: going to mech->get()\n" ;
$mech->get('http://mail.yahoo.com') ;
[download]

And here is the console session:

$ Xvfb :99 &
$ DISPLAY=:99 firefox --display=:99 &
I, MOZREPL : Listening : 127.0.0.1:4242
$ DISPLAY=:99 xdotool search --onlyvisible --title firefox
4194416
$ DISPLAY=:99 xdotool windowfocus 4194416
$ DISPLAY=:99 ~/fillform.pl 
I, MOZREPL : Client connected : 127.0.0.1:46357 : chrome://browser/con
+tent/browser.xul
I, MOZREPL : Client connected : 127.0.0.1:46358 : chrome://browser/con
+tent/browser.xul
debug: going to mech->get()
Can't call method "addProgressListener" on an undefined value at /usr/
+local/share/perl/5.10.1/WWW/Mechanize/Firefox.pm line 574, <DATA> lin
+e 1.
I, MOZREPL : Client closed connection : 127.0.0.1:46358
I, MOZREPL : Client closed connection : 127.0.0.1:46357
[download]

This is line 574:

$source->addProgressListener($lsn,$NOTIFY_STATE_DOCUMENT);