L_BN_VSCROLL

When received, this message indicates that the user has clicked the L_BITMAPCLASS window's vertical scroll bar.

The L_BITMAPCLASS window's parent window receives this code through a WM_COMMAND message from the L_BITMAPCLASS window. Notification occurs before the screen is updated.

Parameter	Description
wParam	Contains the wParam parameter of the WM_COMMAND message, and specifies the child-window ID.
lParam	Contains the L_BITMAPCLASS window handle in its low-order word and the L_BN_VSCROLL code in its high-order word.