well flag can mean a few things. In this case it is really just a switch like on or off.

Code:
'THIS SHOULD BE DECLARED AT THE CLASS LEVEL
Dim myFlag as boolean = false


'THIS WOULD BE IN YOUR DOCUMENTCOMPLETED ROUTINE
If myFlag = False then
    myFlag = True
    'REFRESH FRAME HERE
end if
see, so the flag here ensures the code to refresh the frame only happens once, because you set the flag to true the first time you refresh, so when the routine fires again, it will skip the code since the flag is now true.