The program expands itself to fullscreen so you can't view anything but its interface.
Focus Writer is free, mutliplatform, and open source. It offers live statistics of words, paragraphs, support for dictionaries, tabbed organisation and the possibility to set daily goals.
In addition, one of the most interesting features is the one that allows you to set colors for background, text, papers and the rest of the interface to make it suit your needs and create the perfect environment to write.
Focus Writer is what you need if you are searching a good tool focussed on writing field.