location of mouse, scroll wheel handling

[James Hawkins]

Does anyone know where most of the mouse and scroll wheel actions are
being handled in the code?  For example, say I am surfing the internet
with Internet Explorere and WINE and I use my scroll wheel to move the
page up and down.  Where is the code that handles that?  If anyone has
any ideas whatsoever (or even if you can just say you don't know) I
would really appreciate it.