Hi!
What exactly do you mean by this:
Can we specify which screen definition to use? (how)
You want to know, what aspect ratio to use for specific PC or you want to get resolutions supported by the PC?
Maybe both of those questions aren't even related to what you are asking, sorry if that's so
You may want to check
video_set out. Maybe it might help you out.
Edit: also, for getting info of the current PC configuration, use
sys_metrics.
Best regards!