Originally Posted by eureka
It may be not quite true. Certain types of Cypress TrueTouch capacitive touchscreen (used in PW) can handle thin passive stylus.
I've found mentioning of stylus support
in PW kernel code (look into last spoiler), however, I haven't a PW to test it. It should select finger/stylus/finger+stylus support basing on content of some file in /sys
Passive only means that it is conductive so it couples your body capacitance or EMF to the screen, and does not contain an active signal generator of its own, like old-fashioned wired or battery-powered pucks or stylii. A non-conductive stylus is not likely to work with a capacitive touchscreen.
A fat stylus is only needed for an IR touchscreen. Capacitive touchscreens should work with even a thin piece of wire or conductive thread. A fat conductive stylus should work with either touchscreen technology, such as the one at the ebay link I provided.
Your embedded video only compares capacitive to resistive technology. It doesn't mention IR, which also benefits from differential detection, giving IR a 4K by 4K resolution. You can verify that accuracy on a K5 by rolling your fingertip slightly on the screen while viewing the raw touchscreen data.