In this paper we propose vrLib, a toolkit which aims to make 3D graphical user interface and interaction very easy to design in virtual environments. This project provides well known and new interaction techniques and ready to use widgets, which are totally hardware independent. The main contribution allows to elaborate complex 3D user interfaces in same way it is done in 2D. This toolkit provides adaptive interaction, which means interaction techniques can automatically adapt their behavior to 2D and 3D widgets. This short paper describes the vrLib architecture for construction of 3D interactive applications.