What goes down under the hood when you scroll horizontally with touchpad

[XShayanX]

Hello.
There are some programs that don't support scrolling horizontally (Shift + WheelUp/WheelDown) but you can use WheelLeft/WheelRight to scroll:
Notepad++ (old versions)
Microsoft OneNote for Windows 10

Some other programs don't even support WheelLeft/WheelRight:
Microsoft Excel
AHK Studio

What I noticed is that on all these programs, I can simply use my touchpad to scroll horizontally and it works

I want to know what goes down under the hood, like is some kind of built in Windows DLL is being called? Or what's happening when I use my touchpad to scroll horizontally?

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Also my touchpad acts weird in these situations:

Code: Select all

WheelUp::Send, {WheelUp}

This causes my touchpad to scroll super fast, idk why.

Code: Select all

~WheelUp::Send, {Volume_Up}

This causes my touchpad to scroll slow as hell, and causes AHK to give a HotKeyInterval warning.

I want to know why.