Freeze with Qt4.5 when acceding to Document Settings

[Abdelrazak Younes]

And I cannot make gdb to produce a backtrace... lyx occupying 100% cpu 
and the only way to kill it is with 'kill -9'.

I tested 1.6.1 compiled against Q4.4 but running against Qt4.5 and 
1.6.2svn compiled against Qt4.5.

Qt4.5 is starting to appear in some distribution (already!) so we are 
going to have a lot of bug reports I'm afraid...

Abdel.