On 21/09/16 12:05, Peter Hutterer wrote: > these days a protocol screen like you use it is the exception, not the rule. > > the problem with ScreenNo isn't the ambiguity, it's that it just doesn't > really apply when a screen isn't already plugged in on boot. in many cases, > the screen order isn't clear until after login, e.g. when you use xrandr to > arrange the displays.
The xrandr model, namely all displays just showing parts of a single virtual screen, can cause problems in situations were one screen really serves a completely different purpose from the other screen, i.e. were you really don't want windows to go across screens, or where a screen is linked to an input device that is meant to provides absolute coordinates for one screen only. When I try to use xinput_calibrator to calibrate a touchpanel against its built-in screen, under xrandr it really gets confused about the size of the physical screen versus the size of xrandr's virtual screen. xinput_calibrator opens its window across both my desktop and my Cintiq 13HD, and there is no option to tell it to cover just the latter. Even if there were, there would still be a risk that stylus coordinates at the edge of the tablet could leak into the other screen. Protocol screens used to be a very convenient way to keep screens separate, rather than confuse applications by screens sharing the same coordinate system. If integer protocol screen numbers really are no longer viable, is there no other conceivable way to unambiguously bind the coordinate system of an "absolute" input device to the coordinate system of just one physical output of a graphics card? For example by providing a new option to specify under Section "InputDevice" the identifier of a corresponding Section "Screen" in xorg.conf (just like Option "ScreenNo" "0" did, just not using integers that might depend on hot-plug order, but something that actually refers to a named device driver instance, Port-ID, Bus-ID, whatever). Markus -- Markus Kuhn, Computer Laboratory, University of Cambridge http://www.cl.cam.ac.uk/~mgk25/ || CB3 0FD, Great Britain ------------------------------------------------------------------------------ _______________________________________________ Linuxwacom-devel mailing list Linuxwacom-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxwacom-devel
