a licensing question

["Raven" <qs-raven wp pl>]

Hi.
I've got some questions regarding licensing of GTK.
*1. Is it ok to use GTK to write software, that is proprietary, commercial 
and closed-source?
*2. We are starting writing a toolkit/framework dealing with some "high 
level of abstraction data-to-GUI patterns". Would it be if we made it based 
on GTK+2.0 ?? Essentially it would be :
**2.1. a kind of database engine
**2.2. set of sophisticated GUI controls ("tree view" for example, etc.) 
whose goal is communicating with the database engine

TIA.