Overlaying a touchscreen on top of a tablet PC is an inexpensive and simple way to create a platform for two-handed interaction. The user's preferred hand can use the stylus on the tablet, while the other hand touches the screen directly. For example, such a device could support a painting program that offers a natural way of scrolling around the canvas: simply touch and slide the canvas with your other hand, as you would move a sheet of paper. You could also operate on-screen controls with your other hand without interrupting the work of your preferred hand.
This work was accepted to CHI 2004 and presented in a short paper (PDF, 1.5 Mb). The accompanying video figure (Quicktime, 30.6 Mb) was also accepted for publication at CHI 2004.