The window pops up with all the interaction elements (big area, small area,
text fields, and the selected color area), but no colors are visible.
Neither in the big area (where the 2d color field should be visible), nor
the small area (where the 1d color field normally is shown) displays any
colors.
Selecting one color still works, so clicking the mouse in the empty gray
big area will chose one color, which is shown in the upper right selected
color area, correctly.

(Processing 0124, Windows Vista Business)

are you using the version of processing that includes java, or have you
installed your own?

Installed 1.6.0_01 on my own, and downloaded Processing w/o JRE.

can you try the version that includes the JRE? we don't recommend using 1.6.

most likely this is an issue with java 1.6 not honoring the preferred size
of the component. this happens on linux some times as well, so it's
something we'll need to deal with.

edit]
Buggy color picker

Doesn't work either. I've downloaded Processing w/ Java and confirmed it
uses JRE 1.4.

But now I get a Vista warning that "The color scheme was changed to Windows
Vista Basic" (translated from German). There seems to be some compability
issues ...

Sometimes the color picker shows some skewed colors fragments (see attachment).

yeah, so the color picker is set to go gray rather than doing the warping
thing like that. it's the same issue, there just seem to be some component
sizing problems on vista. this is the second vista bug this weekend so i'll
need to figure out where to get myself a copy and install it on a machine.

please check this one with release 0130, which may have fixed the problem.

Not fixed in 0130, still the same gray area.

fixed for 0136 thanks to a patch from fli.