PHP GUI library/package

Hi All, I have a web project built in PHP which we want to break out part of into a stand-alone GUI program. The architecture is fine - display nicely separated from logic, so coding is not a problem. What I can't work out is what to use for the GUI part. I looked at phpqt but I can't (yet) get that to build on my Linux dev system, let alone code an interface with it. I was also looking a PHP-GTK2, but I'm not sure how cross-platform it would be - this should run on Windows and Macs as well as Linux... Anyone made a GUI PHP application like this, with one of the major toolkits? Cheers Pete