UltraVNC is an open source application that is used to control Windows computers remotely. When UltraVNC is installed and configured, a user can access the host computer from another computer anywhere in the world using the virtual network computing (VNC) protocol. The host computer is displayed in a program window on the client computer that can be expanded to full screen by using the UltraVNC toolbar or by pressing the full screen hot button. Exiting full screen is as easy as pressing that hot button or toolbar icon again to returned to the windowed view of the host computer.
Press "Ctrl" + "Alt" + "F9" to enable the UltraVNC toolbar.
Hover the mouse across the top of the screen to display the toolbar.
Click the full screen button, located second from the left.
Pressing the hotkey combination of "Ctrl" + "Alt" + "F12" will also toggle the full screen view on and off in UltraVNC.