Updated: July 2009
The framework calls this member function when the user clicks a vertically-aligned scroll bar, spin button control, or slider control.
OnVScroll typically is used by applications that give some feedback while the scroll box is being dragged.
If OnVScroll scrolls the contents of the CWnd object, it must also reset the position of the scroll box with the SetScrollPos member function.
This member function is called by the framework to allow your application to handle a Windows message. The parameters passed to your function reflect the parameters received by the framework when the message was received. If you call the base-class implementation of this function, that implementation will use the parameters originally passed with the message and not the parameters you supply to the function.
When you click a spin button control, the value of nSBCode is SB_THUMBPOSITION.
The nPos parameter is a 16-bit value and must be used only for controls whose range value uses 16 bits or fewer.