procedure OpenForm(FormClass: TFormClass; var AForm;
    AOwner:TComponent=nil);
//根据窗口类名建立窗口,如果窗口存在则只激活它
var
  i: integer;
  Child:TForm;
begin
  for i := 0 to Screen.FormCount -1 do
      if Screen.Forms[i].ClassType=FormClass then
      begin
        Child:=Screen.Forms[i];
        if Child.WindowState=wsMinimized then
           Child.WindowState:=wsNormal;
        Child.BringToFront;
        Child.Setfocus;
        TForm(AForm):=Child;
        exit;
      end;
  Child:=TForm(FormClass.NewInstance);
  TForm(AForm):=Child;
  if not assigned(aowner) then aowner:=application;
  Child.Create(AOwner);
end;

function ActiveForm(FormTitle:string):boolean;
//根据窗口标题激活窗口,如果窗口不存在则返回假
var
  i:integer;
  Child:TForm;
begin
  Result:=False;
  for i:=0 to screen.FormCount-1 do
  begin
    Child:=Screen.Forms[i];
    if Child.caption=formtitle then
    begin
      Child:=Screen.Forms[i];
      if Child.WindowState=wsminimized then
        Child.WindowState:=wsnormal;
      Child.BringToFront;
      Child.SetFocus;
      Result:=true;                      
    end;
  end;
end;  

openform(TForm1,Form1);