An Upload uses progressive enhancement to deliver the best possible uploading experience to users without requiring extra developer effort. Features highlights:
- Asynchronous and synchronous (on form submit) file upload
- Multiple file selection
- Removing uploaded files
- Progress tracking * <-----------------------
- File drag-and-drop *
- Cancelling upload in-progress *
(*) These features are automatically enabled if supported by the browser.
Seems like you should take this out of your documentation if it's not actually there. Just an observation..