An application sends the WM_MDINEXT message to a multiple document interface (MDI) client window to activate the next or previous child window.
WM_MDINEXT
wParam = (WPARAM) (HWND) hwndChild; // handle of child
lParam = (LPARAM) fNext; // next or previous child
Parameters
hwndChild
Value of wParam. Identifies the MDI child window. Windows activates the child window that is immediately before or after the given child window, depending on the value of the fNext parameter. If the hwndChild parameter is NULL, Windows activates the child window that is immediately before or after the currently active child window.
fNext
Value of lParam. If this parameter is zero, Windows activates the next MDI child window and places the child window identified by the hwndChild parameter behind all other child windows. If this parameter is nonzero, Windows activates the previous child window, placing it in front of the child window identified by hwndChild.
Return Values
The return value is always zero.
Remarks
If an MDI client window receives any message that changes the activation of its child windows while the active MDI child window is maximized, Windows restores the active child window and maximizes the newly activated child window.
See Also