The demo site shows the ContextKeys property as a way to pass some extra values with the file upload post but it does not work and looking at the source code the property exists but does not appear to be used anywhere in code server side nor client side. I guess it was planned but never implemented.
If this property really worked the control would be much more useful.
If it will never be implemented then it should be removed from the documentation and sample web site.
If this property really worked the control would be much more useful.
If it will never be implemented then it should be removed from the documentation and sample web site.