Keeping the screen active during periods of user inactivity

Some kinds of applications, like presentation software or audio/video players, require the display to be kept active during long periods without user input. But most systems will turn off the display or go to sleep when they detect no keyboard/mouse activity for some time, in order to conserve power. So an application must be able to inform the system that it is active even during times without user interaction.

Proposal:

Add an API that allows a GUI application to prevent the screen from turning off or the screensaver from kicking in due to user inactivity. The application must be able to turn on or off this functionality when appropriate.

On Windows, this API could use SetThreadExecutionState behind the scenes.