For whatever reason, X no longer automagically determines the dots/inch value for the right-hand portrait monitor and, for lack of anything better, defaults to 75 DPI. That scales everything down by
25% 33%, makes the menu fonts eye-crackingly small, and squinches the monospaced terminal font. The fix requires jamming the proper value directly into
/etc/X11/xorg.conf along with all the other stuff:
Section "Monitor" # HorizSync source: edid, VertRefresh source: edid Identifier "Dell2005FP" VendorName "Dell" ModelName "DELL 2005FPW" HorizSync 30.0 - 83.0 VertRefresh 56.0 - 75.0 Option "DPMS" Option "DPI" "98x98" EndSection
One could calculate the actual value, but that matches what X determines for the left-hand landscape monitor.
And then it Just Works…