WM_SYSCOMMAND oddities
问题 An application recieves the WM_SYSCOMMAND message when the user selects a menu item command on the system menu, and so wParam can be SC_CLOSE, SC_CONTEXTHELP, SC_MAXIMIZE, SC_MINIMIZE, SC_RESTORE etc. That's logical. (Of course you can also send these messages by clicking on the minimize, maximize, close buttons etc.) But one can also send the WM_SYSCOMMAND message to send commands to the Windows Shell. For instance, one can display the start menu (SC_TASKLIST), activate the screen saver (SC