Ugly QT fonts for PyQT apps


I am using different python distribution for work. I have installed sip and pyqt from the sources with the different python interpreter, so they got installed to proper locations.

While I can run some qt based apps such as vitables and spyder without any problem, their fonts look really ugly. Without any antialiasing.

But in qtconfig or other qt based apps (even the same vitables installed with the default python) fonts looks beautiful.

Where should I look? Is this the case where the programs installed with different python interpreter do not locate the qt settings?

Thank you,