How to intercept a click on the forms' minimize button

Problem/Question/Abstract:

Does anybody know how to capture the minimize button press and act on it before it actually minimizes the form?

Answer:

You should intercept WM_SYSCOMMAND messages like this:

unit Unit1;

interface

uses
  SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls, Forms, Dialogs;

type
  TForm1 = class(TForm)
  public
    procedure WMSysCommand(var Msg: TWMSysCommand); message WM_SYSCOMMAND;
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.WMSysCommand;
begin
  if (Msg.CmdType = SC_MINIMIZE) or (Msg.CmdType = SC_MAXIMIZE) then
    MessageBeep(0);
  DefaultHandler(Msg);
end;

end.