Provide "natural scrolling" option for mice.

[mgriego]

Many mice support natural/reversed scrolling through libinput these days. This enables mouse natural scrolling throug a separate config option specifically for mice.

[ammen99]

Thanks for the PR, I am however thinking whether it wouldn't be much simpler to simply allow negative mouse scroll speed, as we already have an option for that?

[mgriego]

I would argue that using the natural scrolling option is more inline with what other graphical systems offer as an option and inline with what is expected for libinput.

[marcusbritanicus]

Purely from a user point of view, especially for those migrating from other places (kde/gnome/.../mac/win), it would be nice if we have that check box. But I do not have any opinion on how it's implemented, though.

I do have a small nitpick in the xml file: Instead of <_short>Mouse natural scroll</_short>, it would be preferable to use <_short>Natural scroll</_short>, just as in touch pad configuration. In wcm, this option will appear in the "Mouse" tab, so it will not cause any confusion to the users.

[mgriego]

@marcusbritanicus The scroll speed and cursor speed options are both prefixed with Mouse... ie: https://github.com/WayfireWM/wayfire/blob/master/metadata/input.xml#L226 . To me, this feels similar: it's a shared option that is scoped to mouse vs trackpad.

To be clear, I'm not opposed to that line of thinking. It makes sense that it would be scoped by the mouse vs trackpad input group, so having the config prefix is a bit redundant. My comment is more about consistency.

[mgriego]

@ammen99 Any other concerns here?

[ammen99]

LGTM, thanks!