Пример EnumWindows

unit Wintask1;

interface

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

type
  TForm1 = class(TForm)
    ListBox1: TListBox;
    ListBox2: TListBox;
    procedure FormCreate(Sender: TObject);
    procedure ListBox1DblClick(Sender: TObject);
  private
    function enumListOfTasks(hWindow: hWnd): Bool; export;
    function enumListOfChildTasks(hWindow: hWnd): Bool; export;
  end;

  THoldhWnd = class(TObject)
  private
  public
    hWindow: hWnd;
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.FormCreate(Sender: TObject);
begin
  enumWindows(@TForm1.EnumListOfTasks, Longint(Self));
  if (ListBox1.Items.Count > 0) then
    ListBox1.ItemIndex := 0;
end;

function TForm1.enumListOfTasks(hWindow: hWnd): Bool;
var
  HoldString: PChar;
  WindowStyle: Longint;
  IsAChild: Word;
  HoldhWnd: THoldhWnd;

begin
  GetMem(HoldString, 256);

  HoldhWnd := THoldhWnd.Create;
  HoldhWnd.hWindow := hWindow;

  WindowStyle := GetWindowLong(hWindow, GWL_STYLE);
  WindowStyle := WindowStyle and Longint(WS_VISIBLE);
  IsAChild := GetWindowWord(hWindow, GWW_HWNDPARENT);

  {Добавляем строку с текстом задачи или именем класса и дескриптор в ListBox1.Items }
  if (GetWindowText(hWindow, HoldString, 255) > 0) and
    (WindowStyle > 0) and (IsAChild = Word(nil)) then
    ListBox1.Items.AddObject(StrPas(HoldString), TObject(HoldhWnd))
  else if (GetClassName(hWindow, HoldString, 255) > 0) and
    (WindowStyle > 0) and (IsAChild = Word(nil)) then
    ListBox1.Items.AddObject(Concat('<', StrPas(HoldString), '>'),
      TObject(HoldhWnd));

  FreeMem(HoldString, 256);
  HoldhWnd := nil;
  Result := TRUE;
end;

function TForm1.enumListOfChildTasks(hWindow: hWnd): Bool;
var
  HoldString: PChar;
  WindowStyle: Longint;
  IsAChild: Word;
  HoldhWnd: THoldhWnd;

begin
  GetMem(HoldString, 256);

  HoldhWnd := THoldhWnd.Create;
  HoldhWnd.hWindow := hWindow;

  WindowStyle := GetWindowLong(hWindow, GWL_STYLE);
  WindowStyle := WindowStyle and Longint(WS_VISIBLE);
  IsAChild := GetWindowWord(hWindow, GWW_HWNDPARENT);

  {Добавляем строку с текстом задачи или именем класса и дескриптор в ListBox1.Items }
  if (GetWindowText(hWindow, HoldString, 255) > 0) and
    (WindowStyle > 0) and (IsAChild <> Word(nil)) then
    ListBox2.Items.AddObject(StrPas(HoldString), TObject(HoldhWnd))
  else if (GetClassName(hWindow, HoldString, 255) > 0) and
    (WindowStyle > 0) and (IsAChild = Word(nil)) then
    ListBox2.Items.AddObject(Concat('<', StrPas(HoldString), '>'),
      TObject(HoldhWnd));

  FreeMem(HoldString, 256);
  HoldhWnd := nil;
  Result := TRUE;
end;

procedure TForm1.ListBox1DblClick(Sender: TObject);
begin
  enumChildWindows(THoldhWnd(ListBox1.Items.Objects[ListBox1.ItemIndex]).hWindow,
    @TForm1.enumListOfChildTasks, Longint(Self));

  ListBox2.RePaint;
end;

end.