$WheelUp::
$WheelDown::
    MouseGetPos, m_x, m_y, id, control, 1
    hw_m_target := DllCall("WindowFromPoint", "int", m_x, "int", m_y)
    WinGetClass, class, ahk_id %id%
    WinGet, id_A, ID, A
    If (class == "Notepad++") && (control == "SysTabControl325")    ; Notepad++: ahk_class Notepad++    tab-bar classNN: SysTabControl325    listener-window classNN: Scintilla1
    {
        ControlGet, properTargetWin, Hwnd,, Scintilla1, ahk_id %id%
        PostMessage, 0x319, 0, (A_ThisHotkey == "$WheelUp") ? 0x10000 : 0x20000,, ahk_id %properTargetWin%
    }
    Else If (class == "CabinetWClass") && (control == "SysTreeView321")    ; Windows Explorer's left pane with a tree of folders.
        PostMessage, 0x20A, (A_ThisHotkey == "$WheelUp") ? 120 << 16 : -120 << 16, ( m_y << 16 )|m_x,, ahk_id %hw_m_target%
    Else If (control == "TSTabCtrlClass1")    ; Miranda IM, TabSRMM window's tab-bar classNN: TSTabCtrlClass1    listener-window classNN: RichEdit20W1
    {
        ControlGet, properTargetWin, Hwnd,, RichEdit20W1, ahk_id %id%
        PostMessage, 0x319, 0, (A_ThisHotkey == "$WheelUp") ? 0x10000 : 0x20000,, ahk_id %properTargetWin%
    }
    Else If (class == "HH Parent")    ; Windows built-in *.chm (help files) reader.
    {
        If (control == "SysTabControl321")    ; Left pane's either tab-bar or 2nd tab's contents.
        {
            ControlGetPos,, ya,,, SysTabControl321, ahk_id %id%
            WinGetPos,, yb,,, ahk_id %id%
            If (m_y < ya + yb + 20)    ; Hovering tab-bar.
                ControlSend,, % (A_ThisHotkey == "$WheelUp") ? ("{Ctrl Down}{Shift Down}{Tab}{Shift Up}{Ctrl Up}") : ("{Ctrl Down}{Tab}{Ctrl Up}"), ahk_id %id%
            Else If (id == id_A)    ; Hovering 2nd tab's contents when .chm reader's window is active.
                Send, % (A_ThisHotkey == "$WheelUp") ? "{WheelUp}" : "{WheelDown}"
        }
        Else
            PostMessage, 0x20A, (A_ThisHotkey == "$WheelUp") ? 120 << 16 : -120 << 16, ( m_y << 16 )|m_x,, ahk_id %hw_m_target%
    }
    Else If (class == "AkelPad4" && control == "SysTabControl321") || (class == "IEFrame" && control == "DirectUIHWND2")    ; AkelPad + forgot what else.
        ControlSend,, % (A_ThisHotkey == "$WheelUp") ? ("{Ctrl Down}{Shift Down}{Tab}{Shift Up}{Ctrl Up}") : ("{Ctrl Down}{Tab}{Ctrl Up}"), ahk_id %id%
    Else If (id != id_A) && (class != "Progman")    ; If the cursor hovers an inactive window (and which is not the desktop) - that inactive window should receive a scrolling event (without the activation of that window).
        PostMessage, 0x20A, (A_ThisHotkey == "$WheelUp") ? 120 << 16 : -120 << 16, ( m_y << 16 )|m_x,, ahk_id %hw_m_target%
    Else If (id == id_A) || (class == "Progman")    ; If the cursor hovers the active window or desktop - the regular scrolling event should get sent to the active window.
        Send, % (A_ThisHotkey == "$WheelUp") ? "{WheelUp}" : "{WheelDown}"
    currOpacity := hwndUnderCursor := x1 := y1 := id := id_A := winClass := maximized := winX1 := winY1 := x2 := y2 := winX2 := winY2 := IDactive := control := key := value := Class := properTargetWin := Hwnd := Height := m_x := m_y := ya := yb := hw_m_target := onTop := procName := XWin := YWin := ""
Return