W$CENTER_WINDOW
The W$CENTER_WINDOW library routine moves the window on the screen in order to have the center of the window matching with the center of the screen.
Syntax:
 CALL "W$CENTER_WINDOW" USING windowHandle, [screenIndex]
Parameters:
windowHandle
HANDLE OF WINDOW
Specifies the window to be centered.
screenIndex
PIC 9(n)
Optional parameter. Specifies in which monitor the window should be centered in case that multiple monitors are available. In a multi-monitor environment, the window would be centered in the monitor where it was displayed. Set this parameter to move the window in another monitor and center it there.
Note - the SCREEN-INDEX property of the window will be altered according to this parameter.
Examples:
Example - Display a independent window and center it on the screen
working-storage section.
77  hWin                  handle of window.
 
procedure division.
main.
  display independent graphical window
          color  65793
          with   system menu
          title  "Centered window"
          handle hWin
          event  WIN-EVT
  call "w$center_window" using hWin.