Free Pascal / Lazarus : Why is the "FormCloseQuery" Event not called in my example? - lazarus

Question

I wrote a small testprogram to try out the FormCreate and the FormCloseQuery procedure. The FormCreate works fine, but the FormCloseQuery just doesn't want to execute. Did I overlook something? Pressing the "X" on a form-window or using the close method, both doesn't work!
procedure FormCreate(Sender: TObject);
procedure FormCloseQuery(Sender: TObject; var CanClose: boolean);
(...)
procedure TForm1.FormCreate(Sender: TObject);
beginn
//gets executed without problems
end;
procedure TForm1.FormCloseQuery(Sender: TObject; var CanClose: Boolean);
begin
case MessageDlg('Question', mtConfirmation, [mbyes, mbno, mbcancel], 0) of
mrYes:
begin
ShowMessage('yes');
CanClose := true;
end;
mrNo:
begin
ShowMessage('no');
CanClose := true;
end;
else
begin
ShowMessage('cancel');
CanClose := true;
end;
end;
end;
Here's the full code:
The lpr-File:
program project1;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Interfaces, // this includes the LCL widgetset
Forms, Unit1
{ you can add units after this };
{$R *.res}
begin
RequireDerivedFormResource:=True;
Application.Initialize;
Application.CreateForm(TForm1, Form1);
Application.Run;
end.
The Unit-File:
unit Unit1;
{$mode objfpc}{$H+}
interface
uses
Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls;
type
{ TForm1 }
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure FormCloseQuery(Sender: TObject; var CanClose: boolean);
private
{ private declarations }
public
{ public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.lfm}
{ TForm1 }
procedure TForm1.FormCreate(Sender: TObject);
begin
ShowMessage('FormCreate Procedure wurde gestartet');
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
Close;
end;
procedure TForm1.FormCloseQuery(Sender: TObject; var CanClose: Boolean);
begin
case MessageDlg('Question', mtConfirmation, [mbyes, mbno, mbcancel], 0) of
mrYes:
begin
ShowMessage('yes');
CanClose := true;
end;
mrNo:
begin
ShowMessage('no');
CanClose := true;
end;
else
begin
ShowMessage('cancel');
CanClose := true;
end;
end;
end;
end.

Answer 1

The solution is/was to hook up the form's OnCloseQuery event of the form to this procedure. Here's a short description how to do it:
Bring up and select the form (in my case "Form1: TForm1") in the object inspector (see explanation below).
In the object inspector go to the tab "events"
Locate the "OnCloseQuery"-Event and select "FormCloseQuery" if you already declared and written the procedure as it was the case in my example. (If you haven't declared/implemented it double click in the dropdown box or click on the button next to it, the one with the three dots, an an empty "OnCloseQuery"-procedure procedure will be added automatically. The code editor will jump directly to the new procedure.)
To bring up / select the form in the object inspector, open the object inspector (F11). If you are looking at the code editor bring up the form first (F12) and click on it. This should bring it up in the object inspector. Make sure the form (the top element in the list) is selected and none of it's components (like buttons etc.).
Here's another explanation: http://www.delphigroups.info/2/b2/444056.html