[PULL] prep work for screen crossing fixes

[Michal Suchanek]

On 4 October 2011 07:58, Jamey Sharp <jamey at minilop.net> wrote:
> On Tue, Oct 04, 2011 at 03:35:41PM +1000, Peter Hutterer wrote:
>> On Mon, Oct 03, 2011 at 10:02:28PM -0700, Jamey Sharp wrote:
>> > On Tue, Oct 04, 2011 at 02:15:53PM +1000, Peter Hutterer wrote:
>> > > On Mon, Oct 03, 2011 at 09:02:19PM -0700, Keith Packard wrote:
>> > > > On Tue, 4 Oct 2011 13:26:35 +1000, Peter Hutterer <peter.hutterer at who-t.net> wrote:
>> > > > >       Store desktop dimensions in screenInfo.
>> > > >
>> > > > Do we need the minimum x/y of the desktop too?
>> > >
>> > > is it ever other than 0/0?
>> >
>> > Sure, that's legal (though crazy). Besides the xorg.conf ServerLayout
>> > syntax for positioning a Screen "RightOf", "Below", etc, you can also
>> > set the screen's absolute position.
>>
>> right, that's for a single screen. but can the desktop origin ever be
>> non-zero? Can you have layout where the first screen goes from say -1024..0
>> and the second from 0..1204?

If you do that with xrandr it shifts everything to make the
leftmost/topmost screen start at 0.

At least it used to.

It's not something that should be relied on too much, though, I guess.

There were already people complaining that this shifting breaks their
screen layout (eg. when one screen is turned off temporarily or added
to existing layout, or changes resolution).

>
> I believe that could happen in this kind of config, for example:
>
> Screen "screen1" -1024 0
> Screen "screen2" RightOf "screen1"
>
> I think it might also happen if you did:
>
> Screen "screen1"
> Screen "screen2" LeftOf "screen1"
>
> I also don't think there's anything forcing screens to be contiguous. In
> general I believe the config parser gives you plenty of rope to shoot
> yourself in the foot.

Definitely. Some people are placing their screens some dozens of
pixels apart to account for the screen borders and make the cursor
motion "logical". It's hard to do because you can't rely on --left-of
or such but should be possible.

Thanks

Michal