[STOBJECT]
Implement code to show and hide the power and volume icons in the notification area aka systray.
Control panel applications send WM_USR+220 messages to the systray window in order to show or hide an icon in the systray. The wParam parameter identifies the icon: 1=power, 4=volume. The lParam parameter indicates the new icon status: 0:show, 1:hide.
Control panel applications also send WM_USER+221 messages to the systray window in order to retrieve the current status of a systray icon. The wParam parameter identifies the icon, just like in the WM_SUER+220 messages. The lParam parameter is ignored. The return value indicates the status of the icon: 1:visible, 0:hidden.
svn path=/trunk/; revision=74225