unit Unit1; 

interface 

uses 
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, 
  Dialogs, StdCtrls; 

type 
  TForm1 = class(TForm) 
    Button1: TButton; 
    Edit1: TEdit; 
    procedure Button1Click(Sender: TObject); 
    procedure FormCreate(Sender: TObject); 
  private 
    { Private-Deklarationen } 
  public 
    { Public-Deklarationen } 
    procedure MyIdleHandler(Sender: TObject; var done: Boolean); 
  end; 

var 
  Form1: TForm1; 

implementation 

{$R *.dfm} 

{ TForm1 } 

procedure TForm1.MyIdleHandler(Sender: TObject; var done: Boolean); 
begin 
  // do something here 
  // hier irgendwas tun 
  Self.Left  := Random(Screen.Width - Self.Width); 
  Self.Top   := Random(Screen.Height - Self.Height); 
  Edit1.Text := TimeToStr(now); 
end; 

procedure TForm1.Button1Click(Sender: TObject); 
var  
  dt, dtn: TDateTime; 
begin 
  // simulate heavy calculatin with this button 
  // umfangreiche Berechnungen simulieren 
  dt := Now; 
  repeat 
    dtn := Now; 
  until dtn > (dt + 10 / 3600 / 24); 
end; 

procedure TForm1.FormCreate(Sender: TObject); 
begin 
  // assign the Handler to OnIdle of the Application 
  // den Handler dem OnIdle von Application zuweisen 
  Application.OnIdle := MyIdleHandler; 
end; 

end.