The cicn cursor loader was introduced recently for the Mac SCUMM v6-7
games. I still haven't played Pegasus Prime, but I have forced it to
load all the nine cursors (ID 128-133, 900-901, and 20000) and it seems
to work fine for all of them. At least after I made a few fixes to the
loader itself.
I did get some crashes with the old code when trying to compare them, so
it's possible that we should backport this to 2.9. But I haven't seen
any bug reports about it, so maybe not...?
This fixes transparency for the slider widget handles in v6-7 games.
Someone may want to adjust the image decoder later, but it will do for
now. Not all icons have useful masks, but some do.
When a dialog window is created now, all palettes from the individual
widgets (icons and pictures) are collected and combined into a single
palette. The widget palettes are remapped to this. The icon decoder is
now a proper image decoder, which makes icons and pictures very similar
to handle.