The OpenEdge Hive

Suppose your window has a button that is designed to launch an application, using ShellExecute or CreateProcess, but this application takes a few seconds to launch. Since ShellExecute(Ex) and CreateProcess return immediately after the process is created, an impatient user will have time to press the button several times. To work around this problem you may want to disable the button until the application really becomes visible. WaitForInputIdle does the trick. Well, in reality it waits until the application has its input queue (for mouse and keyboard) empty and waiting, but that's at about the same time anyway.

  
  {windows.i}
  DEFINE VARIABLE hProcess AS INTEGER NO-UNDO. 
  DEFINE VARIABLE ReturnValue AS INTEGER NO-UNDO.
  hProcess = CreateProcess("notepad.exe",
                           "",
                           3). 

  IF hProcess = 0 THEN DO:
      getlasterror().
      ShowLastError().
  END.
  ELSE DO:
     RUN WaitForInputIdle IN hpApi (hProcess, 
                                    -1,   /* -1=INFINITE */
                                    OUTPUT ReturnValue).
     RUN CloseHandle IN hpApi (hProcess, OUTPUT ReturnValue).
  END.

Note

CreateProcess does not search for applications as good as ShellExecute does. When CreateProcess does not find an application you may have more luck with ShellExecuteEx (not ShellExecute itself, because that does not return a hProcess).
ShellExecuteEx will return a hProcess when SEE_MASK_NOCLOSEPROCESS is specified in its fMask field.