For screenshotting a map at a very small zoom level there was the need to have a (virtual) higher screen resolution that the physical monitor in fact has. Luckily most Linux system offer to set such resultion using xrandr. A simple call to set the virtual resolution is:
#!/bin/bash
$ FACTOR=2
$ WIDTH=$(xrandr | grep "\Wconnected" | sed -e "s/.* \([0-9]\{1,4\}\)x\([0-9]\{1,4\}\).*/\1/")
$ HEIGHT=$(xrandr | grep "\Wconnected" | sed -e "s/.* \([0-9]\{1,4\}\)x\([0-9]\{1,4\}\).*/\2/")
$ RES="${WIDTH}x${HEIGHT}"
$ HEIGHT=$(expr "${HEIGHT}" '*' "${FACTOR}")
$ NEWRES="${WIDTH}x${HEIGHT}"
$ xrandr --output DP-6 --mode $RES --fb $NEWRES --panning $NEWRESThis sets the screen size to double the height of the physical screen height and enables scrolling as soon as you hit the edges with the mouse. The values may of coure be adjusted. Also adding more width is possible. The script just doubles the height.