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4/8/2010

This message is sent when a window is being activated or deactivated. This message is sent first to the window procedure of the top-level window being deactivated; it is then sent to the window procedure of the top-level window being activated.

Syntax 

WM_ACTIVATE 
fActive = LOWORD(
wParam); 

fMinimized = (BOOL)HIWORD(
wParam);

hwndPrevious = (HWND) 
lParam;

Parameters

fActive

Value of the low-order word of wParam. Specifies whether the window is being activated or deactivated. It is one of the following values.

Value Description

WA_ACTIVE

Activated by some method other than a mouse click (for example, by a call to the SetActiveWindowfunction or by use of the keyboard interface to select the window).

WA_CLICKACTIVE

Activated by a mouse click

WA_INACTIVE

Deactivated
fMinimized

Value of the high-order word of wParam. Specifies the minimized state of the window being activated or deactivated. A nonzero value indicates the window is minimized.

hwndPrevious

Handle to the window being activated or deactivated, depending on the value of the fActiveparameter. If the value of fActiveis WA_INACTIVE, hwndPreviousis the handle to the window being activated. If the value of fActiveis WA_ACTIVE or WA_CLICKACTIVE, hwndPreviousis the handle to the window being deactivated. This handle can be NULL, and is always NULL when the window being activated and the window being deactivated are in separate processes.

Return Value

An application should return zero if it processes this message.

Default Action

If the window is being activated and is not minimized, the DefWindowProcfunction sets the keyboard focus to the window.

Remarks

The fMinimizedparameter must be zero.

If the window is activated by a mouse click, it also receives a WM_MOUSEACTIVATE message.

Requirements

Header winuser.h
Windows Embedded CE Windows CE 1.0 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also