For anyone with deeper insight into CHDK who may be able to help nafraf sort this out here's what is going on with the zebra "sparkling pixels" in his 1.00a port.
Regardless of type selected I get random sparkling pixels that move around a bit with each blink. They flash at the same frequency that a normal zebra area blinks, but they randomly move around with each blink. (I have 3 other Powershots running CHDK 1.2 to compare normal behavior to.) They seem to be grouped with most in the upper third of screen and fewer in lower third - very few in middle third.
It may be a screen painting/mapping issue. When I point at a light bulb and hold the shutter half way down for 20 - 30 seconds sometimes the proper zebraing will pop into place all by itself (no sparkles anywhere else on screen) every 5th or 6th (or Xth) blink cycle. I've noticed this a time or two today in nafraf's latest build - don't recall it happening in earlier builds. However, it is not reliably repeatable. Depressed the shutter button for over 60 seconds waiting for the magical "alignment" so I could count its frequency, but it didn't happen the last couple of times I tried to see it again.
It's like it is trying to paint the zebra area, but it is starting at the wrong coordinates. And then sometimes (maybe when "some multiple of total pixels"/"zebra pixels" = "approximately an integer") it will show the correct zebra area every x blink cycles. But that's just a guess on my part.