idTimer (ULONG) - input
The value of an application-timer identifier must be below TID_USERMAX to avoid clashes with timers used by the system.
A timer identification, TID_SCROLL, is created by a scroll bar control. An application does not normally see the associated WM_TIMER, but passes it to the scroll-bar control.
A timer identification, TID_CURSOR, is created when the cursor is flashing. An application must ensure that the associated WM_TIMER is passed on to the default window procedure.