message: Focus the composer view on file upload
diff: @@ -450,6 +450,9 @@ export default class ContentMessages {
  },
  };
  + // Focus the composer view
  + dis.dispatch({action: 'focus_composer'})
  +
  // if we have a mime type for the file, add it to the message metadata
  if (file.type) {
  content.info.mimetype = file.type;
  