I do a lot of mix and match with displays and PCs. The one I have now booted to Sid has 2560x1440 and 2560x1080 displays on an old ATI dual DisplayPort PCIe card. I have the larger configured as primary and the smaller as upper via an xrandr script in /etc/X11/Xsession.d/. 14.0.6dev's first greeter appearance after booting is on the upper/smaller display, but moves to the lower/larger display on logging out. I'd rather it always be on the larger. Is this something configurable? If so, where & how? Is this something worth or needing a bug report?