Empirically is seems that gdm 2.26 is appearing on whichever monitor contains the mouse pointer, which in my case at bootup seems to be one pixel right of centre, putting it just onto my secondary monitor. I assume gdm 2.20 tried to pick the primary monitor.
Empirically is seems that gdm 2.26 is appearing on whichever monitor contains the mouse pointer, which in my case at bootup seems to be one pixel right of centre, putting it just onto my secondary monitor. I assume gdm 2.20 tried to pick the primary monitor.