codice:
public function IsFormOpen(strName as string) as boolean
  dim f as form
  IsFormOpen = false
  for each f in Forms
    if f.name=strName then
      ' aperto
      IsFormOpen=true
      exit for
    end if
  next f

  set f=nothing
end function
Sono andato a memoria ma dovrebbe funzionare.

richiami con:
codice:
if IsFormOpen("Form2")=false then
  form2.show
end if