MessageDlg jams screen update

I am having great difficulties with Message box stopping screen update

e.g

..procedure TForm1.FormActivate(Sender: TObject);
begin
Edit1.Visible:=True;
Edit1.SetFocus;
end;

procedure TForm1.Edit1DblClick(Sender: TObject);
begin
Edit1.Visible:=False;
End;

procedure TForm1.Edit1Exit(Sender: TObject);
begin
Label1.Visible:=True;
Label1.Caption:=Edit1.Text;
Application.ProcessMessages;
end;

works as expected.

BUT

Change to

procedure TForm1.Edit1Exit(Sender: TObject);
begin
Label1.Visible:=True;
Label1.Caption:=Edit1.Text;
Application.ProcessMessages;
{******************* }
GetOk;
{*******************}
end;

Procedure GetOk;
Begin
MessageDlg('Testing', mtInformation, [mbOK], 0);
end;

And Edit1 Remains Visible AND Label1 remains hidden until AFTER
MessageDlg is fired..

What am I missing?
Is there any way around this ?

Tanks for any help.
Les

.