The Thinkpad X220 has a screen resolution of 1366x768 (16:9), which suits the size of the 13" screen, but sometimes you stumble on applications that have gui elements that are taller than the screen.
In Linux, it's possible to change the screen scaling to emulate a larger screen with xrandr. It won't look as crisp as the real resolution, but might get you out of a bind.
This command will emulate a 1920x1080 (16:9) screen:
xrandr --output LVDS1 --panning 1920x1080 --scale 1.406x1.406
or 1600x900:
xrandr --output LVDS1 --panning 1600x900 --scale 1.171x1.172
To return to the original scaling, type:
xrandr --output LVDS1 --panning 1366x768 --scale 1x1
On the other hand , if you have for example a 1920x1080 (16:9) screen but would like to
scale down to 1600x900
(which might well be the case when I receive the new 1920x1080 IPS screen for my 14" T430)
xrandr --output LVDS1 --panning 1600x900 --scale 0.8333x0.8333
In XFCE4, you can also magnify the resolution in
Settings->Appearance->Settings->Window Scaling
you can also do this on the command line with
xfconf-query -c xsettings -p /Gdk/WindowScalingFactor -s SCALE
where SCALE is either 1 or 2