Messenger Demo Viewer 1.0Free
Messenger Demo Viewer is a free cross-platform and open source Facebook Messenger viewer that hides your sidebar by default. To show or hide the sidebar, press cmd/ctrl + b.
Facebook Messenger always has a sidebar with all your recent chats, including a part of the last message sent, visible on the screen. This is useful for personal chats, but in a professional demo you'd want that to be hidden.