Hey team ArtRage, great oeuvre of a program you made. Have a bit of my feedback on it. :) I'll sort the suggestions in order of majority. All of the following concerns the "full" version.
Small gripes about the current version 2.2:
1. Setting the layer transparency needs instant feedback.
Doing it in the current version is a chore because you cannot see what your setting does. You click the transparency button, change the value blindly, click OK. Dammit, wrong value, the tint is too dark. You click the button again, change the value blindly... you get the idea. Compared to the streamlined everything-else this is a stopper.
2. A key shortcut or button to merge the current layer.
Would make a lot of neat tricks easier, e.g. approximation of airbrush masks. Airbrush freely on a clear layer, use the eraser to carve the form, merge the layer with one beneath it, repeat.
3. A double click on the pan/zoom/rotate tools should reset the position/zoom/rotation. Right now the only way to do it is via the menu.
4. The layers palette should memorize its position between session.
Right now it always pops up in the middle and I have to drag it back to the upper right corner where I like it to sit, every time I launch ArtRage.
5. A keyboard+mouse way to zoom the canvas.
We have right-click to pan and Alt+right-click to rotate, but no zoom.
6. The brush dab sample in the brush palette might reflect the current color.
Bigger (but still not so labor-intensive) suggestions:
7. Brush presets.
I know it is a can of worms, but the absence of presets is another flow slowdown. Instead of having three sizes of oil brushes, a clear solvent, and a blender at my disposal, which I can just click and pick, I have to tweak little dials all the time. Maybe limit the size of the palette for them, and/or use graphical icons instead of names, so there is little enticement to make a hundred of presets and drown in them. But *some* preset features would be really productive to have. (Even better if they get stored with the painting, too, so you can pick up the work where you left it off.)
8. Wacom tool ID support.
Wacom tools have unique IDs and distinguish between their two tips. This data you get along with positional data from the API. (This is a well-documented feature.) Right now ArtRage ignores both IDs and the tip data. It would be great if I could actually use the eraser as eraser - right now the tool stays the same if I flip the stylus. Better yet, ArtRage should memorize which tool I picked with which stylus tip last and switch to it when the data starts to come from that stylus tip. Painter has this feature, and I have three styli - two regular ones and a soft brush tip - which lets me use five drawing tools interchangeably without ever clicking buttons. Just grab another stylus or flip the one you hold, and the brush (or brush preset) switches. I often hold two styli in my hand, one working and another at ready. It is an invaluable productivity feature. Even with one stylus, an ability to switch between two brushes is invaluable - but ArtRage ignores even that! Pretty pretty pleeeze? *bambi eyes*
9. The color picker... could be better.
The picker is dominated by the sector, with the slider so tiny it is almost lost next to it. At the very least, the slider should be wider! The sector itself is way too big for values and produces redundant hues. (The way it is calculated now has the brighter saturated colors dominate it entirely - it is very hard to pick muted tones.) But it is too small for hues! The rainbow packs it too tightly and makes the hues hard to pick. I do realize that the picker form reflects its position in the corner and is symmetrical to the brush palette, etc. But aesthetics shouldn't hamper usability, should they? Look how Painter's color picker works. The circle of hues and a S/V equilateral triangle. The circle is really a circle, you can move the color toward cold or warm from any spot with no stop between red and purple. The triangle contains not a single redundant color and gives every tone an equal treatment. That's the best color picker ever invented. No need to reinvent the color wheel.
You have "glitter". I am a painter, I have no use for glitter of any form, circular or square or little stars (banish them forever). But oh, for a way to do good realistic splatter! Fine or coarse, even or varied, blotches with tiny droplets at their edges! Shouldn't be too hard: use the same particle engine as glitter, but with different form and without hard metallicity. Only a set of a few dozen scanned splatter droplets used for particle shapes would be needed - and there are such brushes for Photoshop already, so the shapes could be easily obtained.
Potentially major features ( I don't know how hard it would be):
10. Scrap bits for color mixing
There already are nifty reference images that can be pinned to the canvas and moved around; the same interface might be used - just allow drawing on these scraps to mix colors on, put dabs of paint on for color picker, etc. That would be way more hands-on than the little color swatches ArtRage has. You could layer some paint on a scrap palette, load the brush, then paint on the canvas with the beautiful multicolor loaded oil.
11. Paint depth as "paper tooth" for dry media.
Oil paint on a layer above some deep-textured oil paint already works right, its texture reflects the "dried" paint's ridges on the layer below. But dry media revert to the paper grain again! It would be great if you could "gesso" the canvas coarsely with a brush, then "dry" it (lift another layer) and draw with the pencils and crayons on the resulting texture.
12. Scrap bits for color mixing
There already are reference images that can be pinned to the canvas; the same interface might be used - just allow drawing on these scraps to mix colors on, put dabs of paint on for color picker, etc. More hands-on than the little color swatches! You could layer some paint on a scrap palette, load the brush, then paint on the canvas with the beautiful multicolor loaded oil.
13. Imitation of rules.
Someone has already suggested French curves. Why stop at that? Straight rules, tone comparison screens, French curves, ellipse guides... mmm...
14. Paint viscosity, diffusion and resistance.
Probably really challenging to implement, but I couldn't help mentioning it. ;)
Keep up the good work!