I created jQuery plugin with that kind of widget, but really, any type of widget can be built on top of it. What jquery plugin does - used API library to communicate anyway, so if people will want different type of widgets - they will come.
As for support on different platforms - Safari is tricky one right now. Trying to figure out why it is not working. IE before version 10 will not work, because it uses typed arrays in javascript. Other than that it should work in any modern browser in theory.
Have you done tests on many platforms to show which ones are supported?
I'd probably like it to be more automatic... a single clickable progress bar without the need for the 2 text fields or generate button.
But yeah... this is ace.