Editor ImageBrowser - Error Handling for Large Images

I made mistakes in that post.  I'm using the error handler on the imageBrowser of the editor, so clearly it was implemented.

However, I still don't know how to interact with the imageBrowser (and I'm assuming, the fileBrowser when I get there).  I want to cancel the changes that didn't take for now.  Is there a way to interact with the imageBrowser and is there documentation for the details?

Thanks.