For this example to work, you must enable uploads in your web.xml file.
It would also be a good idea to up the limit on file-size a bit, so you can upload
larger files to see the effect ....
This samples shows uploads in a repeater. Notice how your first click to add an upload
row is submitted via XHR, while subsequent clicks are submitted via IframeIO (on supported
browsers), as there are now file fields in the form.
There is another upload sample with on-value-changed handler that submits the form as soon as a file is chosen.
Hint: If you are running the client and server on the same machine, you will need to upload a lot to see the effect, or it will upload so fast, the progress bar will not have time to draw.