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.