After installing lightweight window managers, I noticed that some gtk applications didn't work ( thunar or nautilus, for example ) because of a dbus problem. Moreover, the gtk applications looked ugly, the icons didn't show up.
making dbus run
You have to add the following line to /etc/rc.conf
Don't forget to put the right dbus file in /etc/rc.d
cp /usr/pkg/share/examples/rc.d/dbus /etc/rc.d/dbus
choosing your gtk theme
To solve the second problem, you need to create a .gtkrc-2.0 file in your home directory with the following lines :
gtk-theme-name = "Clearlooks" gtk-icon-theme-name = "gnome"