Hi Yves-Alexis! lightdm is now one of the three packages holding qt4 in testing. Would it be possible for you to apply the patch Moritz sent? If you can't I'll be happy to NMU it.
Cheers, Lisandro. -- Lisandro Damián Nicanor Pérez Meyer http://perezmeyer.com.ar/ http://perezmeyer.blogspot.com/