The absolute z coordinate of pointing device on its tablet at full tablet resolution.
- macOS 10.4+
For the coordinate to be valid, this event must be generated by a tablet pointing device (otherwise the property is set to
0). The z coordinate does not represent pressure. It registers the depth coordinate returned by some tablet devices with wheels; if the device is something other than these,
0 is returned. This method is valid only for mouse events with a subtype of
NSTablet and for events of type