The WM_NEXTDLGCTL message is sent to a dialog box procedure to set the keyboard focus to a different control in the dialog box.
WM_NEXTDLGCTL
wCtlFocus = wParam; // identifies control for focus
fHandle = (BOOL) LOWORD(lParam); // wParam handle flag
An application should return zero if it processes this message.
The effect of this message differs from that of the SetFocus function because WM_NEXTDLGCTL modifies the border around the control.
Do not use the SendMessage function to send a WM_NEXTDLGCTL message if your application will concurrently process other messages that set the focus. Use the PostMessage function instead.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Requires version 1.0 or later.
Header: Declared in winuser.h.
Dialog Boxes Overview, Dialog Box Messages, PostMessage, SendMessage, SetFocus