Detect 5 finger gestures

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http://askubuntu.com – I've owned several Lenovo X-Series tablets. Each of these have touchscreens that support only two simultaneous input points, but Windows is able to recognize up to 5 finger gestures (e.g. 5-finger pinch to lock, 4 finger tap to start the application switcher, 4-finger drag to switch applications, etc.) I've played around with touchegg, but it doesn't seem to be able to detect anything more than two-finger gestures. What trick is being used to accomplish this on Windows? How might I go about implementing something similar for Linux? Other info: X reports the touchscreen as a Wacom ISDv4 E6 F (HowTos)