Offhand, I'd say the version of Qt 5 that comes with libqt5 from experimental is insufficient in some way.
The recommended (and documented) way to build Sigil on Linux is to download/install a binary distribution of Qt5 and build Sigil against that. I think that's where we're at unfortunately ... at least until Qt5 is more mature and mainstream in the various distros' repositories.
This would, of course, be best discussed in the Sigil forum.
Last edited by DiapDealer; 11-04-2013 at 10:27 AM.