Interface:
Pallet Hiding:
There could be a setting for each pallet (tools,color,layer,etc) to disappear when the cursor is away from the edge of the window, appearing when the cursor comes close enough and staying visible until the cursor moves off of the pallet. Perhaps it would be possible to select which edge it uses. Or have each pallet turn into a small icon that you can drag around and 'clip' to a side of the interface. The full pallet window would appear when the user rolls over this icon with the cursor. Or another way would be to have a simple text label for the pallet inside the "tool options" bar at the top. I noticed that it has a ton of extra blank space. Maybe have a section where you can drag pallets to stay as text or icons until the cursor hovers over one of them. This would make it where you never have to touch your keyboard to access a pallet, it would all depend on where your mouse is, just like a hidden taskbar would behave.
Right now: I thought the dimmed opacity and size of each pallet was kind of cool, but it doesn't really clear out the working space enough (at least for me). I have to hit the TAB key constantly as I work, which gives me either a tiny square of canvas or no access to the brush settings, layers,color, etc. Yes, I've tried out "ignore TAB" on the pallets I'd like to keep up. That is a VERY NICE option. I just noticed that you guys seem to be working out ways to get the pallets out of the user's face in one way or another
Please consider the 'hiding' behavior for pallets, it would give users the best of both worlds: a full size pallet when you need it and a full uncluttered canvas when you need to paint and not worry about the interface. Adjust double click timing:
Being able to adjust the double click timing would allow the interface to work more consistently for each user. A lot of times the double click detection is way too fast and I end up clicking haphazardly to select a layer because a normal double click puts it into "edit name" mode.
Hotkeys to show or hide each pallet:
It would be cool to be able to show a pallet near the mouse cursor with a hotkey. Such as the color pallet or swatches. This could also apply to custom pallets.
Right now: it's almost an all or nothing type of thing (aside from ignore TAB of course).
Pallet Scrolling:
Being able to scroll up and down in the brush pallet in the same way the layers pallet works would be nice. The grab and drag behavior is very useful
Right now: the brush pallet ends up extending past the bottom edge of the screen and you have to close other sections to shorten the pallet window and reach that bottom section. Since this grab and drag works on the brushes and layer pallets, why not have it for all of them? Instead of being able to click and drag anytime, how about having a hotkey like CTRL enable grab and drag anywhere inside the pallet?
Layer Pallet:
dragging-
I noticed it's very tricky to drag the layers around. Usually the grab and drag dominates over common layer operations, such as dragging the layer into a folder. Actually, it was only by accident that I could drag a layer into a folder and I was unable to do it again. What about having a drag area for a layer, such as a cross hatched textured section next to the eye icon or on the right of the layer? Clicking this area would only drag the layer itself, not the whole layer pallet contents. Being able to select multiple layers would be great also. Clicking a layer one time to select it
Right now: It feels very haphazard to click and drag layers, sometimes editing the layer's name, or putting it into select mode. I noticed that this edit mode seems to kick in when clicking a few pixels before the right edge of the layer thumbnail. Clicking about 5px-10px around the layer's name kicks in edit mode too. How about making this editing area smaller, to where only clicking the actual text triggers editing? It feels like it's too easy to trigger it currently.
enable hide/show for multiple layers-
In SAI, it's possible to click the eye icon to hide or show a layer, hold the left mouse button (or stylus) down, and drag across other layers to match the visibility of that layer you started on. It's a very fast and efficient way to hide a bunch of layers at once or show them. It's just click, drag, let go, and done.
Right now: I have to click each and every layer I want to hide one by one, it's rather cumbersome.
ALT Click to show only that layer-
In both Photoshop and SAI ALT Clicking a layer's eye icon will hide all other layers and only show that layer. This makes working on a single layer very easy because you can hide all the others with just one click and only focus on your current layer's contents.
Right now: holding ALT turns the cursor into the eye dropper tool which flickers between being a cursor and eye dropper. This also happens for all other pallets even if the canvas is nowhere near the cursor.
Double Click to Minimize Pallets:
Double clicking a pallet's tab could work just like the minimize button between the gear and X does. This would give the user a bigger target to click as opposed to a 13px icon.
Memorize the size of pallets before minimizing:
I noticed that after minimizing and restoring the color pallet when it's "grouped" on top of the layer pallet it will resize itself to be about 50% of the total group's height instead of it's original size.
Drawing & Painting:
CTRL toggles the move tool:
I use this constantly when I draw on the canvas, because I often don't know how large my sketch will be. With a pencil or brush slected, I'll hold CTRL and quickly move my sketch, let go, and the tool switches back to a pencil and I continue drawing. It's a very fast way of adjusting your drawing.
Right now: This isn't possible. I have to CTRL+T to transform, but it's impossible to zoom in or out or use the pan tool to move around the canvas.
Being able to zoom and pan while transforming layer contents
A lot of times, I need to zoom out to see where to place something or make sure it fits within the whole picture I'm working on.
Right now: The transform tool effectively locks your view on the canvas, which limits how far you can drag the transform box or move around.
Global Brush Option Locks:
This is something photoshop has. It's a little lock icon next to an option in the brush pallet. It just makes the "locked" option apply to any other brush you select. Since there are no special types of brushes aside from the eraser, I think this feature could fit easily into the scheme of things. Sometimes it's useful to have things be shared between brushes, like the size pressure option. You could set it for one brush and not have to worry about setting it for other brushes. Or maybe have a right click menu option on the lock icon of "apply the option to all brushes or just this group". This would be especially useful for the perspective guides too!
Right now: When I select a brush, I often have to check and see if the pressure size option is enabled. The graph makes it look a bit more complicated. It would be great to have a "default" pressure sensitivity and lock it for other brushes or have an easy way to go back to the default pressure curve incase you mess it up. The pressure curves are pretty new to me so, it feels kind of odd
But it's a cool option to have.Clear Layer Contents:
In SAI, when I'm sketching I usually hit DELETE when I want to start over and redraw something. This clears the contents of the layer itself without deleting the entire layer from the layers pallet.
Right now: there seems to be no function that does this. I have to CTRL+A, DELETE, then CTRL+D to replicate this process. This one of the reasons I like to use SAI for drawing, it makes the whole process nice and quick.
Crop Tool:
It would be great to have some sizing options and nondestructive cropping where you can go back when selecting the crop tool and redo your crop.
Right now: it's pretty basic, but I like how it shows the size of the box in pixels under the box.
Color History:
The could be a small bar or pallet that holds all your recently used colors. Maybe have a limit to how many it can hold.
Brush History:
Same as above expect it would hold the stroke icon or dab icon of recently used brushes
Rotate textures in Brush:
I noticed you can have a random scale and offset, but how about having a random rotation for a texture in a brush? This would add a lot of variety to a stroke. Also, maybe have an adjustment for how often it rotates. Or maybe actually have it 'spin' as you paint, and being able to adjust the speed of the rotation.
Programmable brushes:
Just a fun idea. What if it was possible to make a brush behave different depending on which color or color range you're paint over? Or give a brush some specific conditions then what would change about the brush. For example, if painting over red, use this texture with a double brush. Or if painting with 50% pressure, use this blue color swatch, else use orange. Any brush option could be used, and the conditions could be things you already use for brush settings like speed, direction, pressure, rotation, fade. Adding canvas things like color range, location range, maybe canvas rotation angle too.
Closing thoughts:
I really admire what you're doing with Paintstorm so far. It's changing the way people create digital art and at a great accessible price. You've also been very bold in creating a GUI from scratch instead of relying on boring old common controls like so many programs do. I thought it was pure genius the way you have the minimum size built right into to size bar by dragging the left end of the bar rightwards. Very slick
I hope you take these ideas into consideration. I'd love to make Paintstorm my to go program for creating art, it shows a lot of promise! Keep up the great work you're doing 
Painterly
