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If you’re using a TrackPoint as your favourite mouse, probably you configured it to allow scrolling with the help of middle button. If not, I suggest to take a look at ThinkWiki.
But those steps explain how to configure vertical scrolling, but what about
horizontal scrolling? If you want to have scrolling in both directions, add the
following section in your xorg.conf file.
Section "InputDevice"
Identifier "Trackpoint"
Driver "mouse"
Option "CorePointer"
Option "Device" "/dev/input/mice"
Option "Protocol" "ImPS/2"
Option "Buttons" "7"
Option "YAxisMapping" "4 5"
Option "XAxisMapping" "6 7"
Option "EmulateWheel" "true"
Option "EmulateWheelButton" "2"
EndSection