For example. Visit Google, make a search. You can swap between "video", "images" and other tabs and that search term will be included - but clicking "news" the search query is not included from the top of the page - it works for the side but not the top.
The black Google navigation bar, offers a shortcut/link to its various products.
For what you are looking for, you will have to try this:
Google News is not completely integrated to offer a search solution. In Search / Images / Maps/ ..., you are looking for information/data - i.e its a search problem. Whereas News is an independent product. And thats the reason, clicking on News link on the Google navigation bar, takes you to a fresh page (without your query).