Brian Heibert wrote: > I am finding that when I display a window twice for example go to > the application menu in OS X and select About this App... then > close the about window (nib) and select About this App.. again I am > getting this error message: > Failed assertion: > fn IsWRefConFBHandle(wRefCon) > at line 951 at RNTM APPEARANCE.INCL > What do I do to fix this? I want the NIB window to be able to be > displayed as many times as the user clicks on the About menuitem. Either  turn off the window's Standard handler checkbox in IB, and close the window via an old-style DoDialog handler for the _wndClose FB event or  immediately after the window is created in your code from the nib, call InstallWindowCloseHandler (see below) passing the window's WindowRef. '--------------------- long if 0 "WindowCloseHandler" enterproc fn WindowCloseHandler( nextHandler as EventHandlerCallRef, theEvent as EventRef, userData as ptr ) = OSStatus '~'1 dim as WindowRef @ w dim as OSStatus result : result = _eventNotHandledErr dim as long wNum call GetEventParameter( theEvent, _kEventParamDirectObject, _typeWindowRef, #0, sizeof( WindowRef ), #0, @w ) wNum = fn FBGetWndNumber( w ) select fn GetEventKind( theEvent ) case _kEventWindowClose // (It's bad to let the standard Carbon handler close the // window, because the FB-specific associated information // doesn't get properly disposed of). window close wNum result = _noErr // we handled end select exitproc = result end if local fn InstallWindowCloseHandler( w as WindowRef ) '~'1 dim as EventTypeSpec events(1) begin globals dim as proc sWindowEventUPP // 'static' var end globals #if def _FBtoC sWindowEventUPP = @fn WindowCloseHandler #else long if ( sWindowEventUPP == 0 ) sWindowEventUPP = fn NewEventHandlerUPP( [proc "WindowCloseHandler" + _FBprocToProcPtrOffset] ) end if #endif // def _FBtoC events.eventClass(0) = _kEventClassWindow events.eventKind(0) = _kEventWindowClose end fn = fn InstallEventHandler( fn GetWindowEventTarget( w ), sWindowEventUPP, 1, @events(0), #0, #0 ) '--------------------- Robert P.