Delphi 中使长循环有响应

//┏━━━━━━━━━━━━━━┓
//┃代码着色：CodeColor v1.0 ┃
//┃来自：悄然无声的 Blog ┃
//┗━━━━━━━━━━━━━━┛

var
b:boolean;

procedure TForm1.Button1Click(Sender: TObject);
begin
b:=true;
while(b) do
begin
Caption:='Working';
Application.ProcessMessages;
end;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
b:=false;
Caption:='Stop';
end;