Получить дескриптор окна другого приложения и сделать его активным

type
  PFindWindowStruct = ^TFindWindowStruct;
  TFindWindowStruct = record
  Caption : string;
  ClassName : string;
  WindowHandle : THandle;
end;

function EnumWindowsProc(hWindow : hWnd; lParam : LongInt) : Bool {$IFDEF Win32} stdcall; {$ELSE} ; export; {$ENDIF}
var
  lpBuffer: PChar;
  WindowCaptionFound: bool;
  ClassNameFound: bool;
begin
  GetMem(lpBuffer, 255);
  Result := True;
  WindowCaptionFound := False;
  ClassNameFound := False;

  try
    if GetWindowText(hWindow, lpBuffer, 255) > 0 then
      if Pos(PFindWindowStruct(lParam).Caption, StrPas(lpBuffer)) > 0 then
        WindowCaptionFound := true;

    if PFindWindowStruct(lParam).ClassName = '' then
      ClassNameFound := True
    else
    if GetClassName(hWindow, lpBuffer, 255) > 0 then
      if Pos(PFindWindowStruct(lParam).ClassName, StrPas(lpBuffer)) > 0 then
        ClassNameFound := True;

    if (WindowCaptionFound and ClassNameFound) then
    begin
      PFindWindowStruct(lParam).WindowHandle := hWindow;
      Result := False;
    end;

  finally
    FreeMem(lpBuffer, sizeof(lpBuffer^));
  end;
end;

function FindAWindow(Caption : string; ClassName : string) : THandle;
var
  WindowInfo : TFindWindowStruct;
begin
  with WindowInfo do begin
    Caption := Caption;
    ClassName := ClassName;
    WindowHandle := 0;
    EnumWindows(@EnumWindowsProc, LongInt(@WindowInfo));
    FindAWindow := WindowHandle;
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  TheWindowHandle : THandle;
begin
  TheWindowHandle := FindAWindow('Netscape - ', '');
  if TheWindowHandle = 0 then
    ShowMessage('Window Not Found!')
  else
    BringWindowToTop(TheWindowHandle);
end;