ClipCursor(left, top, right, bottom)
Confines the cursor to a rectangular area on the screen.
Parameters
left, top, right, bottom : (int, int, int, int)
contains the screen coordinates of the upper-left and
lower-right corners of the confining rectangle. If this parameter is omitted or (0,0,0,0), the cursor is free to
move anywhere on the screen.Win32 API References
Search for ClipCursor at msdn, google or google groups.