应用程序发送系统消息

// 通过向系统发送消息，可以完成一些系统任务。
HWND hWnd = ::FindWindow(_T("Shell_TrayWnd"), NULL);

if (hWnd != NULL)
{
        // 显示桌面
	::PostMessage(hWnd, WM_COMMAND, MAKELONG(407, 0), NULL);
}

具体的消息如下：

Serial.	Msg Number	Description Of The Message
1.	305	Displays the Start menu
2.	401	Displays Run Dialog
3.	402	Displays Logoff Dialog
4.	403	Command to cascade all toplevel windows
5.	404	Command to Tile Horizontally all top level windows
6.	405	Command to Tile Vertically all top level windows
7.	407	Shows the desktop. Do look at message number 419.
8.	408	Shows the Date and Time Dialog
9.	413	Shows taskbar properties
10.	415	Minimize all windows
11.	416	Maximize all windows. To see the effect of this command first do Minimize and then Maximize all.
12.	419	Well I am a bit confused about this message. This also shows the desktop. Maybe somebody can notice the difference.
13.	420	Shows task manager
14.	421	Opens Customize Taskbar Dialog
15.	424	Locks the taskbar
16.	503	Opens Help and Support Center Dialog
17.	505	Opens Control panel
18.	506	Shows the Shutdown computer dialog
19.	510	Displays the Printers and Faxes dialog
20.	41093	Displays Find Files Dialog
21.	41094	Displays Find Computers Dialog