The TBM_GETTIC message retrieves the logical position of a tick mark in a trackbar. The logical position can be any of the integer values in the trackbar's range of minimum to maximum slider positions.
TBM_GETTIC wParam = (WPARAM) (WORD) iTic; lParam = 0;
Returns the logical position of the specified tick mark or - 1 if iTic does not specify a valid index.