closed source application using gtk?

[Stephan Kotze <Stephank tuks co za>]

I'm new to this newsgroup, and to opensource in general so please bear
with me. 

Am I allowed to write closed source commercial software using the gtk
libraries, and not pay for using gtk? (unlike qt)
(I have to write a program for a large firm that requires a gui)

Thus far I have ascertained that I can if I dynamically link to the gtk
libs, because gtk uses the lesser-gpl.

I am not 100% sure that I am correct though.
I have scoured gnu.org's faq, Im just not entirely sure.

Thanks

Stephan Kotze