Your suggestions have been taken in count. Now the code has been adapted to
the arrows direction, and a cool effect has been introduced: animating when
collapsing or expanding a title. Well it is just adding the line
d->treeView->setAnimated(true) but is more cool than before.

You can go to http://www.ereslibre.es/kdedev to check out the new
screenshots, or you can visit this to take a look at the code:

http://www.ereslibre.es/kdedev/highlight.php?id=kdelibs/kutils/kpluginselector.cpp

http://www.ereslibre.es/kdedev/highlight.php?id=kdelibs/kutils/kpluginselector.h

http://www.ereslibre.es/kdedev/highlight.php?id=kdelibs/kutils/kpluginselector_p.h

Bye and thanks,
Rafael Fernández López.