The TBM_GETCHANNELRECT message retrieves the size and position of the bounding rectangle for a trackbar's channel. (The channel is the area over which the slider moves and which contains the highlight when a range is selected.)
TBM_GETCHANNELRECT
wParam = 0;
lParam = (LPARAM) (LPRECT) lprc;
Parameters
lprc
Pointer to a RECT structure that contains the size and position of the channel's bounding rectangle when the function returns.
Return Values
No return value.
See Also