If you use a touchpad, the mouse scroll distance is a float value, not just 1 or -1. Currently when scrolling in geany, it scrolls 4 (in my experience) lines seriatim. Instead you could use the float value to perform more fine scrolling (at least 1 line at once) and save the unused rest to a static variable. For example when the static variable's value is -0.3 and the scroll distance is -0.2, the distance is firstly multiplied by that scroll factor 4, which gives -0.8, then the static variable is added. The result is -1.1, thus it scrolls one line up and the static variable becomes -0.1.