TForm * __fastcall GetParentForm(TControl *ctrl)
{
    if(ctrl==NULL || ctrl->Parnet==NULL)return NULL;

    while(ctrl->Parent!=NULL)ctrl=(TWinControl *)ctrl->Parent;

    if(ctrl->InheritsFrom(__classid(TCustomForm)))return ctrl;
    else return NULL;
}

function GetParentForm(Control: TControl): TCustomForm;
begin
  while Control.Parent <> nil do Control := Control.Parent;
  if Control is TCustomForm then
    Result := TCustomForm(Control) else
    Result := nil;
end;

function ValidParentForm(Control: TControl): TCustomForm;
begin
  Result := GetParentForm(Control);
  if Result = nil then
    raise EInvalidOperation.CreateFmt(SParentRequired, [Control.Name]);
end;