The TBM_GETPTICS message retrieves a pointer to an array that contains the positions of the tick marks for a trackbar.
TBM_GETPTICS wParam = 0; lParam = 0;
Returns a pointer to an array of DWORD values. The elements of the array specify the logical positions of the trackbar's tick marks, not including the first and last tick marks created by the trackbar. The logical positions can be any of the integer values in the trackbar's range of minimum to maximum slider positions.
The number of elements in the array is two less than the tick count returned by the TBM_GETNUMTICKS message. Note that the values in the array may include duplicate positions and may not be in sequential order. The returned pointer is valid until you change the trackbar's tick marks.