RFE: new screen mode to only show screens with movies when a movie is playing.

[i30817]

This is my 'idea' for a 'no fuss' option for single screen (and thus larger screen) gaming for the DS and 3D.

In most games the secondary screen is just used for a map or a menu (or the 3ds at least, since on the DS it's usually not interactable).

So the idea was:

1. enable a shortcut to switch between top and bottom screens and only show one.
2. unless one or two of the screens are playing FMV. If one is playing, put it in fullscreen, if both are playing, put both in fullscreen on their 'natural' order (with the gap optionally).
3. return to the configuration in 1 after all the videos stop playing.

A alternative to 1. and 2. if the information there is really important and requires user input is to overlay or place on top a smaller version of the secondary screen (on the same modes) for a larger than expected 'main screen', except on FMVs where both would jump to their natural size at monitor resolution for a nondistorted FMV.

Would make the (3)ds games a more traditional 'console experience' for the games where the secondary screen is not important except for video cutscenes.

I have no idea if melonds is HLE enough to recognize movies playing, and this would fail with games using engine cutscenes but that's the idea. The current alternative of just ignoring the secondary screen for the gameplay screen size can cause you to miss cutscenes or required user input easily.