Android 中改变Dialog 的位置，去掉title

对于下面的程序有些不理解，求指点！
AlertDialog.Builder ab = new AlertDialog.Builder(this);
                         
                                AlertDialog dlg = ab.create();        //                                LayoutInflater factory = LayoutInflater.from(this );
//                         
//                                View view = factory.inflate(R.layout.aboutpop, null);
                                dlg.setCanceledOnTouchOutside(true);//设置dialog外面点击则消失
                                Window w=dlg.getWindow();
                            WindowManager.LayoutParams lp =w.getAttributes();
                            dlg.onWindowAttributesChanged(lp);  
                            lp.x=20;
                            lp.y=0;                             //   dlg.setView(view);
                                dlg.show();
方法二：
requestWindowFeature(Window.FEATURE_NO_TITLE);
  getWindow().setFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND,
  WindowManager.LayoutParams.FLAG_BLUR_BEHIND);