Staz,
  Responding to your suggestion I exercised all the code I thought might
cause the problem and, well, crash for yourself ;^) 
  Run the code in the FB^3 editor with the FBII runtime.  Select Bomb
under the Bomb menu.
  Changing the WINDOW OUTPUT 5 statement to WINDOW 5 fixes things.  As I
said, this code runs ok under FBII.
  As for me, as soon as soon as I can get my reset button fixed, I'll
continue with the conversion.
  Regards, Charles P.

LOCAL FN wndBuild
  window 5,"Stealth Bomber",(5,40)-(560,340),_docZoom
  edit field 1, "Pogo", (10,10)-(100, 30),,_framed
  window 1, "Dummy", (580,360) - (750, 450), _docZoom

  menu 1, 0, _enable, "Bomb"
  menu 1, 1, _enable, "Bomb"
  menu 1, 2, _enable, "Quit"
END FN

local fn wndCalc
  window output 5
  EDIT FIELD 1,,,_statFramedInvert
end fn

local fn doMenus
  select menu(_itemID)
    case 1
      fn wndCalc
    case 2
      end
  end select
end fn

on menu fn doMenus

fn wndBuild

do
handleevents
until 0