STk is a Scheme interpreter which can access to the Tk graphical package. Concretely it can be seen as the John Ousterhout's Tk package where the Tcl language has been replaced by Scheme. The Scheme interpreter is now R4RS conformant. This release provides an efficient object oriented system called STklos. STklos is a full OO system with multi-inheritance, generic functions, multi-methods and a true meta object protocol).