Existing user interface toolkits are based on a single user interacting with a single machine with a relatively fixed set of input devices. Today's interactive systems, however, can involve multiple users interacting with a heterogeneous set of input, computational, and output capabilities across a dynamic set of different devices. The abstractions that help programmers create interactive software for one kind of system do not necessarily scale to these new kinds of environments. New toolkits designed around these environments, however, need to be able to bridge existing software and libraries or recreate them from scratch. In this position paper, we examine these new constraints and needs. We look at three strategies for software toolkits that help to bridge existing toolkit models to these new interaction paradigms.