Does this step on the unistroke patent that Xerox holds that they used to sue Palm over Graffiti?

Looks like that patent was invalidated in 2004. http://en.wikipedia.org/wiki/Graffiti_(Palm_OS)#Lawsuit

Nope. Read the next sentence:

"Xerox appealed the ruling and won, obtaining $US 22.5 million in retrospective licensing fees. Palm and Xerox agreed to not sue each other for seven years over certain patents, without publicly specifying which patents."

Issued in 1997, so if everyone just ducks low and hides from Xerox for the next 5 years...

Why was it called $1 Gesture Recognizer? On the original project page they don't mention this.

The name isn't all that obvious, but from what I recall of the original talk by Jake Wobbrock, he intended the recognizer to be very simple and easy to implement [edit: and computationally simple] (as opposed to HMMs or the like). This is alluded to in the pdf of the linked paper: "we present a “$1 recognizer” that is easy, cheap, and usable almost anywhere in about 100 lines of code."

It seems like it's mentioned in the paper already (see abstract). Probably not the best name, but it is pretty catchy.

Great stuff!

I have this idea for a long time to use this gesture recognizer (at the time I found this implementation https://github.com/preble/GLGestureRecognizer) to create an App prototyping application.

Today, sketching is the fastest way, but it's very bad quality. Apps like AppCooker let you create better quality mockups but are much slower to use.

Imagine if you could just draw a T and a tableview would show up, same thing for buttons, navbars, etc.

Anyways, thanks for sharing and I'll let you know when I use it!

You should also check out the SILK project: http://www.youtube.com/watch?v=VLQcW6SpJ88 by James Landay, now also at the University of Washington.