隱藏back鍵的bar 隱藏status bar
this.window.decorView.systemUiVisibility = View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN or View.SYSTEM_UI_FLAG_HIDE_NAVIGATION window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS) // 跟系統表示要渲染 system bar 背景。 window.statusBarColor = Color.TRANSPARENT