Author: Jonas Bilinkevicius

I need to create a messagebox asking the user to reply either Yes or No, but with a 
timeout. Is there a way to use a messagebox function with some timeout, like open 
messagebox with Yes or No, and after 20 seconds reply with other information to 
know that user is out?

Answer:

Solve 1:

Show the MessageBox in another thread and kill the thread when you want to remove 
the messagebox under program control:

1   { ... }
2   var
3     ThreadId: Integer;
4     ThreadHandle: Integer;
5     MsgResult: Integer;
6   
7   function thread_proc(p: Pointer): integer; stdcall;
8   begin
9     MsgResult := MessageBox(0, 'Some question?', 'Hey', MB_ICONQUESTION or MB_YESNO);
10    ThreadHandle := 0;
11    EndThread(0);
12  end;
13  
14  procedure TForm1.Button1Click(Sender: TObject);
15  var
16    counter: integer;
17  begin
18    MsgResult := IDNO; {default answer}
19    {show MessageBox}
20    ThreadHandle := BeginThread(nil, 0, @Thread_proc, nil, 0, ThreadID);
21    counter := 20; {wait for 20 seconds}
22    while (ThreadHandle <> 0) and (counter > 0) do
23    begin
24      Sleep(1000);
25      counter := counter - 1;
26    end;
27    {if MessageBox is still visible after 20 seconds, remove it}
28    if Counter = 0 then
29      TerminateThread(ThreadHandle, 0);
30    if MsgResult = IDYES then
31      { ... }
32    else
33      { ... }
34  end;



Solve 2:

35  procedure TForm1.Button1Click(Sender: TObject);
36  var
37    R: Integer;
38  begin
39    Timer1.Interval := 20000;
40    Timer1.Enabled := true;
41    R := MessageDlg('Yes or no?', mtConfirmation, [mbYes, mbNo], 0);
42    Caption := IntToStr(R);
43    Timer1.Enabled := false;
44  end;
45  
46  procedure TForm1.Timer1Timer(Sender: TObject);
47  var
48    F: TForm;
49  begin
50    F := Screen.ActiveForm;
51    if fsModal in F.FormState then
52      F.ModalResult := mrYesToAll;
53  end;