Well, in fact there is a way to do this, but it is not the one I would suggest.

If you go to you $QTDIR/mkspecs/<your_spec> you will see qmake.conf file which will probably have this line
Qt Code: 
  1. QT			+= core gui
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You might want to add all the libs that you need. Let's say you add 'network' to QT. So you have
Qt Code: 
  1. QT			+= core gui network
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But, if you create another projects they will include this module even if you don't need it.