I'm looking for a way to handle this, too. Has anything been done to create an error handler for the imagebrowser and filebrowser?
Right now, an error with the ImageBrowser is getting picked up by the editor's error handler. However, I can't tell there what or where the error was. Also, I'm testing this by attempting to delete an image and having it fail. When this happens, the image in the ImageBrowser disappears, even though the web service failed and didn't actually delete the image. If I exit and re-enter (or change to another folder and then return), the image shows up again.
I'd like to be able to programmatically handle the error, and also tell the ImageBrowser to do something like a CancelChanges so that the image remains if it couldn't be deleted.