Early-generation touchpads do not send periodic calibration frames for baseline subtraction, and are very temperature sensitive, so would slowly drift out of a calibrated state when under load. Escape this by taking the last frame before we decide that the pad is idle as a finger-free baseline.
Early-generation touchpads do not send periodic calibration frames for
baseline subtraction, and are very temperature sensitive, so would slowly
drift out of a calibrated state when under load. Escape this by taking
the last frame before we decide that the pad is idle as a finger-free
baseline.

Tested on:	iBook G4

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