Hi!, I'm back with a new ask!

I'm trying to do a unified toolbar on mac. The unique problem i am having is that the icon bottom appears to be greater than other applications (i have uploaded a pic comparing my application (at left) and the dropbox settings panel (at right)

Captura de pantalla 2013-04-22 a la(s) 19.35.42.png

You can see that my toolbar has an unwanted space at bottom, just below the QAction button, and the dropbox one (as any other OS X application) hasn't.

How could i fix it?

Regards!