How to display a menu items for a node but not for it's parent I have a page which I don't want to appear in a menu unless the user is already on that page or a child page underneath it.

For example on a shopping site, I would like to have a 'special offers' page positioned in the menu under the 'products' page, but it would only be visible if you're on the special offers page and not from the products page.

E.g. the standard menu

Home
    Products
    Contact us 


When on the special offers page:

Home
    Products
         Special offers
    Contact us


Is there a way this effect can be achieved?
you could use Menu blocks and play a bit with the "Visibility settings"