This version of mrdoob's and rhyolight's Harmony application aims to provide some extra functionality including:

• better palette (bounds + slots interpolated between those)
• undo/redo
• gradient background (x/y/others?)
• scanfill brush

Currently it provides following extra functionality:

• mirroring (x, y, radial)
• "sticky" palette (shift). Note that it's not possible to paint under the palette!
• vertical constraint (hit s while painting)
• horizontal constraint (hit a while painting)
• perspective constraint (hit d while painting, set target with f)

You can find more information about Harmony at http://mrdoob.com/blog/post/689.

See also http://rhyolight.posterous.com/new-brushes-for-harmony-canvas-app.

To run, just open harmony.html in a canvas-enabled web browser.