How to show progressbar and Cancel file downloading to dropbox server in Saver

[Cross-linking for reference: https://stackoverflow.com/questions/30451730/how-to-show-progressbar-and-cancel-file-downloading-to-dropbox-server-in-drop-in ]

1) Per the documentation, you can implement the progress callback function, which will occasionally get called with a progress value you can use to update whatever progress UI you want.

2) The Saver doesn't currently offer the ability to cancel the operation once it's been started by the user. (In case the concern is using the user's bandwidth, note that the operation doesn't use the user's own network bandwidth, as the operation is performed directly between the Dropbox servers and the supplied URL of the file.)

3) There's no size limit on the Dropbox Saver.