#include <WinAPI.au3>

$tRect = DllStructCreate($tagRECT)
DllStructSetData($tRect, "Left", 20)
DllStructSetData($tRect, "Top", 50)
DllStructSetData($tRect, "Right", 200)
DllStructSetData($tRect, "Bottom", 200)

$tPoint = DllStructCreate($tagPOINT)
DllStructSetData($tPoint, "X", 120)
DllStructSetData($tPoint, "Y", 120)

MsgBox(4096, 'PtInRect', _WinAPI_PtInRect($tRect, $tPoint))