The following messages are associated with trackbars.
Size and Position
TBM_GETCHANNELRECT
TBM_GETTHUMBLENGTH
TBM_GETTHUMBRECT
TBM_SETTHUMBLENGTH
Slider Position
Line and Page Size
TBM_GETLINESIZE
TBM_GETPAGESIZE
TBM_SETLINESIZE
TBM_SETPAGESIZE
Range
TBM_GETRANGEMAX
TBM_GETRANGEMIN
TBM_SETRANGE
TBM_SETRANGEMAX
TBM_SETRANGEMIN
Selection
TBM_CLEARSEL
TBM_GETSELEND
TBM_GETSELSTART
TBM_SETSEL
TBM_SETSELEND
TBM_SETSELSTART
Tick Marks
TBM_CLEARTICS
TBM_GETNUMTICS
TBM_GETPTICS
TBM_GETTIC
TBM_GETTICPOS
TBM_SETTIC
TBM_SETTICFREQ