The head of my old PC was a CTR Philips Brilliance 15A. This specific monitor hasn't any geometry settings in the front panel, just the basic (contrast, brightness and volume controls). It was arrived with an application that gives the customer all the controls needed to control the screen.So far so good.
The problem was appeared in games! Once a game started, the monitor went in DirectX mode, loosing all desktop geometry settings, and of course, there was no ability to run the above software! So, how was it possible to do the geometry settings I needed without leaving the desktop and staying in game mode (DirectX)?
This problem motivated me to create an application that switch a Windows desktop to DirectX mode. Using some basic functions of DirectX API, I was able to write a small piece of software, called DXSwitcher.
This app can be downloaded from here.