But there still is a problem, i never call any API before
>Can u give me a sample of how to call the Win32 API SetWindowPos()?

Click the link to the W i k i in my sig, there's several examples for using API functions. This topic http://fox.wikis.com/wc.dll?Wiki~VFPHelp~VFP specifically shows how to use SetWindowPos


Thanks to u all for helpping , now i can cover the entire screen with my form even the taskbar, i can stop the ALT+TAB key from functioning....

but there is still a problem,i dont know what the name of this key (the key with a window icon next to the CTRL key and the ALT key), when i press it
the taskbar appeal.