They probably meant 'window', i.e. what application had their focus. That's probably also not a very good metric though, given that developers will often flip between editors, terminals and browsers rapidly. It compares with 2004, although it doesn't specify in what area; I'm sure that single-application focus is also highly dependent on the area of work and the software used. Some people can do all their work in one application, others need half a dozen or more.

Also, iä! fhtagn!