Author: Tomas Rutkauskas

How can I close a MessageBox()

Answer:

You can use a thread to achieve that: 

1   unit MsgThread;
2   
3   interface
4   
5   uses
6     Windows, Messages, SysUtils, Classes, Controls, Forms, StdCtrls, ExtCtrls;
7   
8   type
9     TMboxThread = class(TThread)
10    private
11      { private declarations }
12    protected
13      procedure Execute; override;
14    public
15      constructor Create;
16    end;
17  
18  type
19    TFrmMsgThread = class(TForm)
20      BtnClose: TButton;
21      Edit1: TEdit;
22      Edit2: TEdit;
23      Timer1: TTimer;
24      procedure BtnCloseClick(Sender: TObject);
25      procedure Timer1Timer(Sender: TObject);
26    private
27      FFirst: boolean;
28      FMboxThread: TMBoxThread;
29      FWinHandle: HWnd;
30    public
31      { public declarations }
32    end;
33  
34  var
35    FrmMsgThread: TFrmMsgThread;
36  
37  implementation
38  
39  {$R *.DFM}
40  
41  { TMboxThread }
42  
43  constructor TMboxThread.Create;
44  begin
45    FreeOnTerminate := True;
46    inherited Create(False);
47  end;
48  
49  procedure TMboxThread.Execute;
50  begin
51    { Place thread code here }
52    MessageBox(Application.Handle, 'Text', 'Caption',
53      MB_APPLMODAL + MB_SETFOREGROUND);
54  end;
55  
56  { TForm1 }
57  
58  procedure TFrmMsgThread.BtnCloseClick(Sender: TObject);
59  begin
60    FMBoxThread := TMBoxThread.Create;
61    FFirst := true;
62    Timer1.Enabled := true;
63  end;
64  
65  procedure TFrmMsgThread.Timer1Timer(Sender: TObject);
66  begin
67    Timer1.Enabled := false;
68    if FFirst then
69    begin
70      FWinHandle := GetForegroundWindow;
71      FFirst := false;
72      Timer1.Enabled := true;
73    end
74    else
75      SendMessage(FWinHandle, WM_CLOSE, 0, 0);
76  end;
77  
78  end.