evdev and Emulate3Buttons

[Andreas Schuldei <andreas@schuldei.org>]

i have been bug hunting in X in connection with warp@d.o event
interface (available with 2.6 kernel) and his X driver to that,
which is in experimental.

the problem was that the "button depress" event was deferred
untill the "button release" event occured. as a consequence,
everything which had to to with dragging the mouse (marking text,
moving windows...) did not work.

i followed the signal through the layers and the deferral happend
in the Emulate3Buttons section, where the events are generated.
i think that was in
./xc/programs/Xserver/hw/xfree86/common/xf86Xinput.c

the problem does not occure if the Emulate3Buttons optionis not
specified in the config file. everything works as expected.

it would be good if this was documented somewhere, and if someone
else could varify that this works as described above.  Zephaniah
and me are both not sure why this is not triggered with normal
mice drivers, too.