WM_MOUSEWHEEL top-level constant
int
const WM_MOUSEWHEEL
Sent to the focus window when the mouse wheel is rotated. The DefWindowProc function propagates the message to the window's parent. There should be no internal forwarding of the message, since DefWindowProc propagates it up the parent chain until it finds a window that processes it.
Implementation
const WM_MOUSEWHEEL = 0x020A;