Can someone explain to me why the ImageView is not appearing above the LinearLayout?
I had an similar problem by creating a custom optionsMenu. The simplest way to set z-order of views was to do it programmatically. If you want to switch the order sometimes, your should easily call:
ImageView yourImageView = (ImageView)findViewById(R.id.rev_arrow);
yourImageView.bringToFront();
I don´t know if it is adaptive to your application, but in my case it works perfect. If you need more code, let me know.