Osu: Add support for changing slider bar values via mouse scroll wheel

[2str8]

Add an ability to scrolling on slider thing by mouse wheel. Might be useful by setting accurate offset to audio.

[bdach]

You can use arrow keys already, but scroll wheel might also be nice... although it could be a little wonky in case of slider bars inside of scrolling containers.

I guess in that case you could say that if the mouse is hovered over a slider bar, it should increment/decrement it, and if it's not hovered over a slider, then it should scroll?

[2str8]

Yes, that's exactly what I meant.

[Shompi]

Also maybe make it so it only changes the slider value when the screen or panel is not scrolling (full stop) plus on hover to prevent unexpected or non on purpose slider value changes.

[peppy]

We cannot make it based on hover. It will interrupt vertical scrolling.

If we're going to support this, sliders need to have a focus mode, where you click them first to select then you can use the wheel to adjust.

Or they should handle horizontal scroll only.

[LastExceed]

Or require a modifier key to be held