what does "+"(preferred) means in xrandr?

[Aaron Plattner]

"preferred" generally means that the Extended Display Information Data
(EDID) from the monitor indicates that that mode most closely matches
the native timings of the display. All modes listed by RandR for a given
monitor should work with that monitor, but the preferred mode should
work best (for some definition of "best").

RandR will send events when the list of modes for an output changes. To
receive those, you should use XRRSelectInput() to select for them. I
*think* the mask you want it RROutputChangeNotifyMask.

You can get more information about RandR resources and requests in
randrproto.txt:
https://gitlab.freedesktop.org/xorg/proto/randrproto/blob/master/randrproto.txt

On 11/24/18 8:20 AM, pengyixiang wrote:
> hello everyone！
>     What the “preferred" means in xrandr?  Is it setted by display
> hardware? Can we set it manual? If we call “XOpenDisplay” to open
> default screen and then poll the returned x11_fd, will we interrupted
> for “preferred" changed? Is there others docs about it? Looking forward
> to your reply.
> 
> 
> Cheers，
> Pencc