Remote Desktop Manager for Mac supports different User Interface Styles (sometimes known as skins). These greatly influence the visual aspect of the User Interface as well as its mode of operation. Two styles currently exist:
To select the User Interface style you must go in File - Preferences - User Interface.
User Interface - Options
The ribbon is Remote Desktop Manager for Mac default style that sports an advanced control called ribbon. Icons and text makes it easy to learn what feature exists.
RDM main screen - Ribbon style
Classic is Remote Desktop Manager for Mac previous generation style, it holds a standard menu to invoke commands.
RDM main menu - Classic style