Mouse buttons 4 and 5 for scrolling instead of zooming?

Hi,

I'm using ipe-7.2.7-x86_64.AppImage. The vertical scrolling actions on my touchpad (stroking upwards / downwards with two fingers) zooms the canvas. Would it be possible to bind them to pan (== scroll) the canvas instead?

I'm not sure whether "other buttons" in the following comment from mouse.lua also refers to buttons 4 and 5 (scroll wheel actions):

-- If your mouse has additional buttons, then you can also use
-- button8, button9, and button10.
-- (It seems other buttons are not passed through by Qt.)

I tried setting button4 = "pan" in mouse.lua, but that didn't seem to have any effect.

Thanks for any pointers!
-mandar