In Windows 7 when the following option is turned on:
This results in incorrect behaviour with the Wacom tablet, where the drawing strokes appear without the pen touching the tablet.
Disabling the option from Windows addresses the issue, as it seems to be intercepting the stroke and processes them as drag down and up.
When using Harmony the behaviour is somewhat different; hidden strokes are not created, but when you draw, and the flick is intercepted, if your stroke ends outside of the drawing view it will keep on drawing while your pen is hovering over the drawing view until you draw a new stroke again.
Toon Boom Studio 5
Toon Boom Studio 6