Input redirection: don't need X server changes for augmented events

[Deron Johnson]

Hi Keith,

Earlier, I had proposed that we allow the input redirection client to
stick information in the sequence number of the picked events and that
we implement a change to the X server to allow the input redirection
client to turn off the normal writing of event sequence numbers that
are set to it. I withdraw this proposal. I don't think we need this
anymore.

The last time we discussed this issue, you had suggested trying to use
XSendEvent to have the input redirection client send two events instead.
I prototyped this and it works very well. Whenever the Picker sends
an event to the X server that has 3D information associated with it
the Picker first sends a ClientMessage event containing a reference
to the 3D information. This event is only sent for events which
hit 3D objects; it is not sent for events which hit X11 windows.
The extra event has no perceivable effect on event latency and
the throughput effect of sending of 32 bytes of extra data per
3D event is inconsequential.

So I withdraw the proposal I had earlier labelled "Event Control
Miscellany". I no longer need the switch to turn off event sequence
number writing and there is no need to disable the default button grab
(I wanted to do this for 3D misses, but I decided it is not necessary).
There is still the issue of making sure that button events get sent
to the picker-chosen window, but I feel that this is a part of the
other input redirection work that we are planning to do.