; from https://autohotkey.com/board/topic/69464-how-to-determine-a-window-is-in-which-monitor/
; Tells you which monitor a window is on (given a windowhandle)
GetMonitorIndexFromWindow(windowHandle)
{
    ; Starts with 1.
    monitorIndex := 1

    VarSetCapacity(monitorInfo, 40)
    NumPut(40, monitorInfo)

    if (monitorHandle := DllCall("MonitorFromWindow", "uint", windowHandle, "uint", 0x2))
        && DllCall("GetMonitorInfo", "uint", monitorHandle, "uint", &monitorInfo)
    {
        monitorLeft   := NumGet(monitorInfo,  4, "Int")
        monitorTop    := NumGet(monitorInfo,  8, "Int")
        monitorRight  := NumGet(monitorInfo, 12, "Int")
        monitorBottom := NumGet(monitorInfo, 16, "Int")
        workLeft      := NumGet(monitorInfo, 20, "Int")
        workTop       := NumGet(monitorInfo, 24, "Int")
        workRight     := NumGet(monitorInfo, 28, "Int")
        workBottom    := NumGet(monitorInfo, 32, "Int")
        isPrimary     := NumGet(monitorInfo, 36, "Int") & 1

        SysGet, monitorCount, MonitorCount

        Loop, %monitorCount%
        {
            SysGet, tempMon, Monitor, %A_Index%

            ; Compare location to determine the monitor index.
            if ((monitorLeft = tempMonLeft) and (monitorTop = tempMonTop)
                and (monitorRight = tempMonRight) and (monitorBottom = tempMonBottom))
            {
                monitorIndex := A_Index
                break
            }
        }
    }

    return monitorIndex
}

; Windows monitors are numbered from 1 up.
; Find the windowhandle for the 'active' window
; (might be none!)
GetMonitorIndexForActiveWindow()
{
    winHand := WinExist("A")
    if !winHand
        return 0

    return GetMonitorIndexFromWindow(winHand)
}



; Maximize current window
#PgUp::
WinMaximize, A
return

; Minimize current window
#PgDn::
WinMinimize, A
return

; Make active window take up top half of active monitor
#Up::
;Get the index of the monitor the active window is on (1, 2, etc. 0 if no active wind)
monIdx := GetMonitorIndexForActiveWindow()
if (monIdx)
{
    ; Get bounding box of that monitor
    SysGet, MonBnd, Monitor, %monIdx%
    ; monitor height
    monHi := (MonBndBottom-MonBndTop)
    ; monitor width
    monWid := (MonBndRight - MonBndLeft)
    ; half height
    newHi := monHi/2
    WinMove, A, , %MonBndLeft%, %MonBndTop%, %monWid%, %newHi%
}
return

#Down::
;Get the index of the monitor the active window is on (1, 2, etc. 0 if no active wind)
monIdx := GetMonitorIndexForActiveWindow()
if (monIdx)
{
    ; Get bounding box of that monitor
    SysGet, MonBnd, Monitor, %monIdx%
    monHi := (MonBndBottom-MonBndTop)
    ; monitor width
    monWid := (MonBndRight - MonBndLeft)
    newTop := MonBndTop + (monHi/2)
    newHi := monHi/2
    WinMove, A, , %MonBndLeft%, %newTop%, %monWid%, %newHi%
}
return