For example I have:
If some desperate developer scrolls down here, I have another option to do it. Which also disables scrolling as far as I experimented with it. The idea is to use View element like this one in a RelativeLayout, under all your UI elements.
So it is set to be "gone" before some condition. And then you set it's visibility to VISIBLE when you want to disable your UI. Also you have to implement OnClickListener for this View. This onClickListener will catch click event and won't pass it to the underlying elements.