message: Allow left/right arrow keys to navigate through the autocompletion list
diff: @@ -670,6 +670,31 @@ export default class MessageComposerInput extends React.Component {
  onKeyDown = (ev: KeyboardEvent, change: Change, editor: Editor) => {
  this.suppressAutoComplete = false;
  + this.direction = '';
  +
  + // Navigate autocomplete list with arrow keys
  + if (this.autocomplete.state.completionList.length > 0) {
  + if (!(ev.ctrlKey || ev.shiftKey || ev.altKey || ev.metaKey)) {
  + switch (ev.keyCode) {
  + case KeyCode.LEFT:
  + this.moveAutocompleteSelection(true);
  + ev.preventDefault();
  + return true;
  + case KeyCode.RIGHT:
  + this.moveAutocompleteSelection(false);
  + ev.preventDefault();
  + return true;
  + case KeyCode.UP:
  + this.moveAutocompleteSelection(true);
  + ev.preventDefault();
  + return true;
  + case KeyCode.DOWN:
  + this.moveAutocompleteSelection(false);
  + ev.preventDefault();
  + return true;
  + }
  + }
  + }
  // skip void nodes - see
  // https://github.com/ianstormtaylor/slate/issues/762#issuecomment-304855095
  