Program IFSTest;
var
  F, Form: TForm;
  Labl: TLabel;
  Button: TButton;
  Edit: TEdit;
  Memo: TMemo;
  Stop: Boolean;
procedure MyOnCloseQuery(Sender: TObject; var CanClose: Boolean);
begin
  CanClose := Stop;
end;
procedure c2(sender: TObject);
begin
  f.Close;
end;

procedure buttonclick(sender: TObject);
var
  l: TLabel;
  b: TButton;
begin
  if Length(Edit.Text) < 5 then 
  begin
    f := TForm.Create(self);
    f.Width := 100;
    f.Height := 100;
    f.Position := poScreenCenter;
    f.BorderStyle := bsDialog;
    f.Caption := 'Error';
    l := TLabel.Create(F);
    l.parent := f;
    l.Left := 10;
    l.Top := 10;
    l.Width := 100;
    l.Height := 50;
    l.Caption := 'Invalid name';
    b := TButton.Create(f);
    b.parent := f;
    b.Left:=10;
    b.Top := 40;
    b.Caption := 'OK';
    b.Default := True;
    b.Cancel := True;
    b.OnClick := @C2;
    f.Visible := True;
    form.Visible := False;
    while f.Visible do
     begin
       Application.HandleMessage;
     end;
      Form.Visible := True;
  end else begin
    writeln('debug:'+Edit.Text);
    Stop := True;
    Form.Close;
  end;
end;
Begin
  Form := TForm.Create(self);
  Form.Width := 400;
  Form.Height := 300;
  Form.BorderStyle := bsDialog;
  Form.BorderIcons := [];
  Form.OnCloseQuery := @MyOnCloseQuery;
  Form.Caption := 'Name';
  Form.Position := poScreenCenter;
  Labl := TLabel.Create(Form);
  Labl.Top := 120;
  Labl.Left := 160;
  Labl.Caption := 'Please type in your name:';
  Labl.Parent := Form;
  Edit := TEdit.Create(Form);
  Edit.Font.Name := 'Tahoma';
  Edit.SetBounds(160,160,80,24);
  Edit.Parent := Form;
  Button := TButton.Create(Form);
  Button.Left := 160;
  Button.Top := 200;
  Button.Width := 80;
  Button.Height := 24;
  Button.Caption := '&OK';
  Button.OnClick := @buttonclick;
  Button.Parent := Form;
  Button.Default := True;
  Memo := TMemo.Create(Form);
  Memo.Left := 10;
  Memo.Width := 380; 
  Memo.Top := 10;
  Memo.Height := 100;
  Memo.Text := 'Welcome to Form Test.'#13#10#13#10'Type here your name (min 5 letters).  You can''t exit this demo without it.';
  Memo.Color := 0;
  Memo.Font.Color := $FFFFFF;
  Memo.Parent := Form;
  Memo.Readonly := True;
  Form.Visible := true;
  stop := false;
  while Form.Visible  do
  begin
    Application.HandleMessage;
  end;
  Button.Free;
  Form.Free;
End.