This is just some advice for the correct behaviour if you're planning to
implement touch support, please also read
http://who-t.blogspot.com/2012/02/multitouch-in-x-multitouch-touchpads.html

Direct touch mode:
This applies to e.g. cintiq's or TPCs where we want the touch to happen
wherever the user touches on the screen. For those, just send the touches as
they occur and _do not_ send pointer events. The server will do pointer
emulation on the first touch when applicable.

Dependent touch mode:
This applies to all other devices that are more like a touchpad. For those,
the behaviour must be the following:
The first touch does not generate touch events but pointer events only.
When another touch is detected, generate TouchBegin for _both_ touches at
the current position. Do not generate pointer events anymore.
For additional touches, only generate touch events.

When the second touch is lifted (i.e. only one touch remains), generate
TouchEnd for both touches at the current position. Do not send touch events
for the remaining touch, only send pointer events again.

There's a bit of leeway in the protocol but I think we should focus on the
above first before we start exploring.

Gestures:
If the driver interprets any touch events for gestures, it must not send
touch events for those gestures. A client cannot discern between touch
events and already-modified events from driver gestures, so you'd get
duplicate event handling. So for two-finger scrolling, etc. only send the
pointer events and no touch events at all.
For touch sequences that don't convert into an in-driver gesture send touch
events as described above.

Cheers,
  Peter

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