I use dosbox game launcher for my dosbox needs (been too lazy to learn how to use regular dosbox). However Dark Sun: Shattered Lands has problems with mouse lag/sluggishness. It only affects moving your mouse upwards/downwards. Moving the mouse sideways is very responsive, but it feels like moving it through a puddle of oil or grease when moving up and down, and the cursors starts lagging behind if I shake the mouse up and down rapidly.
The solution can be found from here: Darksun: Shattered Lands mouse movement issues

http://www.dosbox.com/wiki/Dosbox.conf
I've tried
fullresolution = 1350x1080
fullresolution = original
windowresolution = 1350x1080
windowresolution = original
Yet none of them work. What am I doing wrong?