Thank you guys for the comments!
"You guys planning to move to Nashorn when it releases with Java8?"
We don't have a position on Nashorn yet, though we'll definitely make tests with it at some time. Currently we are only 3 people working on JAW, and since it's not a for-profit endeavor we cannot afford to work on it full time. For this reason we have to make choices about what to focus on and what to leave out. We've chosen to stick with JavaFX 2 but no doubt we'll look more into Nashorn, hopefully with the help of other developers.
We very much love this project because we believe there are huge opportunities by further separating client (within the browser) and server. Probably the single best advange is that all representation and formatting is done on the client - which also has a broad range of Java libraries at its disposal - whereas the server can stop worring about that and focus instead on handling data and serving data.
Nashorn "want to use scripting because of its dynamic style" and "The main advantage of having JavaScript running on the JVM is that it gives access to the vast array of pre-written Java libraries". We think this is indeed in line with what we are doing, so we'll definitely look for a deeper integration with Nashorn.
"I'm quite concerned with the speed of this right now."
When you load an app it runs like a "normal" standalone program. JAW is not an extra layer on top of which the app runs. The difference is that an app jar is loaded dynamically and instead of writing your own stage (as in JavaFX parlance) you're given a Pane from the browser where you can add your components. Possibly the only overhead is the SecurityManager which is used to sandbox the app. This means that you are not allowed to execute risky actions like read/write to a file or open an HTTP request, but instead you need to ask permission to the browser with calls similar to
1
| String response = jaw.httpGet(YOUR_URL_HERE); |
However, we think this little overhead is compensated by the fact that a user can safely run your app and not be frightened or bothered by some popup that basically tells him his computer is gonna explode if he accepts to run the program "unrestricted"

"Is this going to become a browser such as Chrome, IE, Firefox, etc, or is it fitting a more specific niche?"
Nice question actually, not dumb at all! At the moment it's a niche, we programmers are that niche. We want it to growth though, because clearly everyone can benefit from a larger audience. If you mean "mainstream as Chrome/IE/Firefox", well... we really wish that

On the other hand if you mean "technically as Chrome/IE/Firefox", then no. Differently from current browsers, we wish to have a rich client with better performance and which has access to a vast number of libraries with no need to resort to plugins or browser-specific components. We are not competing with Chrome/IE/Firefox, and despite the fact that we couldn't actually compete with them, there really is no reason to. I've absolutely no idea whether the guys at Mozilla would like or even consider something like this, but if they did we would actually love to collaborate and build something cool together rather then compete. Our efforts on JAW are not aimed at building the best next web browser to overshadow Firefox or Chrome. We want instead to raise awareness around this that we consider a cool idea, and try to involve more people like us that can bring an idea to reality.
"Can have thumbnail before I download it?"
http://imgur.com/VyLlRl9You can also watch some videos here
https://www.youtube.com/channel/UC-hO5Pi2IsfSK4DOScAN1RQIs there somebody here who would like to give it a try and write a simple game?
Thank you ra4king and SHC for the feedback, we'll try to solve that ASAP