Configuring secondary display with Gnome3 and Fedora 21/22

Assuming a laptop with a HiDPI resolution of 2880x1620, and a secondary screen of 1920x1080, this is what you need to do to configure the secondary display to be on the left of the laptop display:

xrandr --output [VGA1|HDMI1|HDMI2] --auto --pos 0x0 [--scale 2x2] --output eDP1 --auto --pos 3840x0

For the same to be on the right side:

xrandr --output eDP1 --auto --pos 0x0 --output [VGA1|HDMI1|HDMI2] --auto --pos 2880x0 [--scale 2x2]