An application sends this message to a multiple document interface (MDI) client window to instruct the client window to activate a different MDI child window. As the client window processes this message, it sends WM_MDIACTIVATE to the child window being deactivated and to the child window being activated.
Parameter |
Description |
wParam |
When the application sends the WM_MDIACTIVATE message to its MDI client window, the wParam parameter contains the window handle of the MDI child window to be activated. When the client window sends the message to a child window, wParam is TRUE if the child is being activated and FALSE if it is being deactivated. |
|
lParam |
When received by an MDI child window, the lParam parameter contains in its high-order word the window handle of the child window being deactivated and in its low-order word the window handle of the child window being activated. When this message is sent to the client window, lParam should be set to NULL. |
MDI child windows are activated independently of the MDI frame window. When the frame becomes active, the child window that was last activated with the WM_MDIACTIVE message receives the WM_NCACTIVATE message to draw an active window frame and caption bar, but it does not receive another WM_MDIACTIVATE message.