Using 4.2.1, I ran into some wierd problems running
Qt Code: 
  1. fname2=QFileInfo(fname).canonicalFilePath()
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with multiple threads. The function was occasionally getting mixed up between threads and returning incorrect results.

So, I mutex'ed it out and everything was fixed. But it was a big deal because I had to use the same mutex on every occurance of QFileInfo throughout my application. I thought that QFileInfo was supposed to be re-entrant ....?