Some applications check for the device id of the device generating the gesture before processing the gesture. One such feature that can be enabled if a real track pad is connected is the Asian Trackpad handwriting feature. If a trackpad is connected and the gesture is performed on the trackpad only then will this feature work.
The gesture software will utilise the same device id of a connected trackpad to cater for any features or applications that are testing the source of the gesture. If no trackpad is found then gestures uses its own ‘dummy’ device id. Gestures can be forced to use its own id, even if a trackpad is connected, if the setting gesturedefaultdeviceid=1 is defined in the UPDD Setting file.
You can use the command line utility to set this value as required; i.e. uppdutils nodevice set gesturedefaultdeviceid 1.
We observed that using OS X's "trackpad handwriting" feature with Gestures works much better under OS X 10.9 than under OS X 10.8. Under 10.8 we found trackpad handwriting with Gestures to be inconsistent and occasionally it won't detect when a finger has been lifted. Under 10.9.1 this did not appear to be the case.