Hey,
so i havent gotten a chance to read this whole thread yet, since its numerous pages long..
but ill still suggest a few things.
sorry if they have already been mentioned.
for color selection; one thing that i really like, and use with most programs i can is numerical values.
In MSpaint, and Corel Painter IX, both have color sliders as well as Hue, Sat, Lum numerical options.
I choose most of my colors, and have memorized color combinations off of their number values. So I dont know if you have this included.. or if its just straight sliders. I seem to spend way too much time playing with sliders than need be.
atleast one transparency that you can set to any color, like in MSpaint. Nothing even fancy, with different percentages of transparency. Just full or not.
Layers. Layers would be super beneficial. And again, not even necessarily have to worry about it being at different opacity percentages. Just plain layering, nothing fancy. For such things as tracing sketches, or for pattern experimenting.
For colors.. If you could have a finished image.. and color slider the whole thing.. Not sure what the proper term is, but you can do it in Painter IX, and photoshop. Where you adjust all colors together, so their ratios are all the same, but changing together.. So you can turn the whole thing red, or blue, or green, etc.
Lastly, which goes along with Alex
is I like a clean workspace. The programs I use are MSpaint (which already has nothing to it..), Corel Painter IX, and Adobe Illustrator. With Painter IX and Illustrator I like to try and have as least as possible options and featurs open.
As I need something Ill pull it open from the top, and then close its window after.. or minimize it.
So, Im not saying anyting fancy like mouse over options.. or minimizing each section.. But if you could turn things on or off.
And access it at the top bar. MSpaint has this option under View. I refer to that, because that seems to an industry minimum standard.
Just my few suggestions. sorry if these are all repeats, or if you have these done already.