I've reported QTBUG 30251 affecting Qt 4.8.x, which is a regression bug (worked OK in 4.7.4) that seriously affects multithreaded apps. I provided suggested corrective code in qthread_unix.cpp and qthread_win.cpp in function QThreadPrivate::finish(). The gist of the bug is that the user QThread::finished() handling slot is called before attributes running and finished are set, and the slot may attempt to delete a still-running thread. The Qt Project (Thiago) has acknowledged and resolved the bug. A fix will be included in Qt 4.8.5.
While I'm able to download the Qt-released qt-everywhere-opensource-src-4.8.3.tar.gz and apply the fix, I am unable to locate the Ubuntu-modified 4.8.3 which is distributed with Mint 14.1. Installing the release 4.8.3 with my fix, while it enables my app to run successfuly, breaks some Mint-distributed software--notably hplip hp-setup and hp-systray.
I've emailed notices and a request for download link for the Ubuntu-modified Qt 4.8.3 to email@example.com and to other mint email addresses, multiple times, without response. All the Qt 4.8.3 sources I can locate online are the Qt released version, not the version as modified by Ubuntu and distributed by both Ubuntu and Mint. I have to say I'm keenly disappointed especially that Mint is unresponsive.