Changes the active window. The specified window is placed in front of all other windows and all keyboard commands will apply to this window. You cannot call this function as an exit command (see Page Properties) or from a Cicode Object.
Note: This function is not supported in the server process in a multiprocessor environment. Calling this function from the server process results in a hardware alarm being raised.
The window number (returned from the WinNumber() function). Be aware that this is not the same as the window handle, returned from the WndFind() function.
0 (zero) if successful, otherwise an error is returned.
! If two windows are displayed;
! Changes the active window to Window 1.
! Changes the active window to Window 0.