Dropbox chooser enhancements

[dev_webdam]

Working with the dropbox chooser, there were a couple pieces of enhancements I think would be useful for developers. 

Getting a reference to the opened window would allow us to programatically close it through JS. 
More events than just 'sucess' and 'closed'

I noticed that if I open the chooser and use the provided button, the window resets. Not sure if this is a bug, but if I do this a couple times, then choose something, the success callback is triggered multiple times, once for each time that the chooser was reopened. 

[Greg-DB]

Thanks for the post. I've sent this along as a request for a way to get a reference to the window. I can't promise if or when that might be implemented though. 

As for the potential bug, I'm not sure if I follow the scenario exactly. Can you elaborate and provide some mored detailed steps for reproducing it? Perhaps you can also share a screencast if that would be helpful? Thanks in advance!