Apple did a ATG Human Interface Group project that publicly demonstrated a mac tablet (not newton) gesture interfaces at WWDC, early 90's. The tablet was a pen and one finger, both could be used at same time but only one finger (single layer of ITO). Not long after AT&T gave Apple a multi-touch (five fingers) transparent panel using a XY matrix ITO, it was integrated into tablet. At about the same time, Apple discussed with a display manufacturer about developing a mixed mode display, modify the XY display drivers to sense fingers as well as drive display. cool stuff