Little bug with pop up menus (? and other controls) on web pages. On the following page, if you select the pop up menu with the list of pages in the article (to the right of the title), select the first page, so that the control is still selected with a blue border. Now scroll down the page with a scroll wheel on the mouse, or using the window scroll bars (not space or the arrow keys), so that the control is off the top of the page. Now hit the space bar or the up and down arrows. The control gets drawn off the window at the top of the screen on top of the menu bar, rather than scrolling the page further.
http://arstechnica.com/articles/cult...ceshifting.ars