Service robots require interactive programming interfaces that allow users without programming experience to easily instruct the robots. Systems following the programming by demonstration (PbD) paradigm that were developed within the last years are getting closer to this goal. However, most of these systems lack the possibility for the user to supervise and alter the course of program generation after the initial demonstration was performed. In this paper we present an approach, where the user is able to supervise the entire program generation process and to annotate, and edit system hypotheses. Moreover, the knowledge representation and algorithms presented enable the user to generalize the generated program by annotating conditions and object selection criteria via a 3D simulation and graphical user interface. The resulting PbD-system widens the PbD approach in robotics to the interactive generation of flexible robot programs based on demonstration and annotations.