[sugar] cursor jumpiness

[Mikus Grinbergs]

G1G1; Q2D16; Joyride, manually updated to 2146.

Just now experienced an episode of "jumpiness" with my cursor.  What 
was unusual was that I was using an external USB mouse (and an 
external USB keyboard) -- my hands were nowhere near the XO 
touchpad.  [By "jumpiness" I mean that for a small movement of the 
mouse, the cursor would "jump" to someplace further from the 
starting point than intended.  Not sure about this, but some jumps 
might have been at an angle to the mouse movement.]

I'm now thinking that some of the unexpected cursor behavior that 
many have noticed - might come not from variances in SENSING the 
user's input, but rather from variances in INTERPRETING (in 
software) the sense data that had been received.  Or it might even 
be due to "interference" having corrupted the 'sense data' from how 
it had actually been reported by the input device.

[I have no reason to think that my (optical) mouse suddenly started 
emitting  "position" information differently.  Normally, my XO 
cursor moves smoothly when I move my mouse.]

mikus