message: Mac sends lowercase event.key even when holding Shift unlike Windows
diff: @@ -672,6 +672,7 @@ export default class RoomView extends React.Component<IProps, IState> {
  handled = true;
  }
  break;
  + case Key.U: // Mac returns lowercase
  case Key.U.toUpperCase():
  if (isOnlyCtrlOrCmdIgnoreShiftKeyEvent(ev) && ev.shiftKey) {
  dis.dispatch({ action: "upload_file" });
  