The TBM_GETRANGEMIN message retrieves the minimum position for the slider in a trackbar.
TBM_GETRANGEMIN wParam = 0; lParam = 0;
Returns a 32-bit value that specifies the minimum position in the trackbar's range of minimum to maximum slider positions.
TBM_GETRANGEMAX, TBM_SETRANGE, TBM_SETRANGEMAX