Is it me, or is that an odd way of doing it. Maybe that's one of the reasons they want the icon system replaced...
Oh how easily we forget the days of 8 bit graphics and color look up tables! :-)
Back in those days the Amiga system was never designed to work in a 24bit graphics system. Back then we had 256 colors tops - and damn it, we liked it! :-D
If I'm not mistaken, anything could "steel" (also known as locking) pens or colors on the WB screen. The backdrop image for example could also use up some of those colours, and the system would always lock the colors needed for window outlines and text. Considering the limitations, this was indeed a pretty clever way to display images on screen where the colors available (or even the number of colors to choose from) are undefined and completely arbitrary.
Unfortunately it doesn't make much sense once you get into the TrueColor, non-mapped GFX world. Of course it's no secret that all TrueColor GFX solutions for the Amiga are nothing more then really well thought out hacks, and for the most part work seamlessly, but there are times when the Amiga's 8 bit GFX past comes back to haunt us! :-)
Anyway, I would expect all this to be ironed out with time.
- Mike