WM_ACTIVATE消息

参数:

fActive  = LOWORD(wParam);   // activation flag 
fMinimized = (BOOL)HIWORD(wParam); // minimized flag 
hwndPrevious= (HWND)lParam;   // window handle

fActive 参数主要定义了该窗口发生了什么事情，即该窗口是被激活还是被取消。该信息保存在 wParam 的低阶字中，可以取以下的值：

-------------------------------------------------------------------------------------- 
值                                     描述 
-------------------------------------------------------------------------------------- 
WA_CLICKACTIVE       通过鼠标单击激活了该窗口 
WA_ACTIVE                   通过鼠标以外的工具（如键盘）激活了该窗口 
WA_INACTIVE               取消该窗口的激活 
--------------------------------------------------------------------------------------

示例代码:

case WM_ACTIVATE: 
{ 
     // test if window is being activated 
     if(LOWORD(wParam)!=WA_INACTIVE) 
     { 
          // application is being activated 
     } 
     else 
     { 
          // application is being deactivated 
     } 
} 
break;

转自：http://blog.csdn.net/guoqiang721029/archive/2005/03/18/322758.aspx