I'm in the process of creating a desktop screen capture application. I'm using a Timer to poll for screen changes. Can I detect if the desktop has changed through a Windows API?
As far as I know there is no easy API for this. The only way to do it more efficiently would be to use a mirror driver which would capture all screen events (e.g., the way remote desktop does it).
You could try the UltraVNC mv2 mirror driver: http://www.uvnc.com/products/mirror-driver.html