I have a 14 inch ultrabook with a resolution of 2560x1440. I currently run Gnome 3.16 in HiDPI mode with a scaling factor of 2. Since I'm unable to specify a factional scaling factor, like 1.5, I've opted to use xrandr to scale desktop for me.
xrandr --output eDP1 --scale-from 3200x1800 --panning 3200x1800
I've put the above in a script that runs shortly after logging into a Gnome session. There a couple problems with this.
- Sometimes the scaling is lost, like when an on-screen display appears, e.g., pressing one of the brightness controls on the laptop keyboard; and
- watching Netflix full-screen only overlays an additional video image over the browser only occupying top left of the laptop screen.
Regarding #1, the scaling isn't completely lost but the desktop 'shrinks' and only appears in the top left corner leaving black space to the right and bottom of the visible desktop. It appears the 'shrunk' desktop is the scaled one but stuck in the top left corner of the 3200x1800 screen.
I'm hoping if I can configure X to do the scaling, and avoid running xrandr, that the screen will stay scaled.