Help me understand Lightroom's graduated filter

[JClishe]

In Martin Evening's Photoshop Lightroom 3 book, he says, and I'm paraphrasing, that you click where you want the effect to start (maximum strength), and drag to where you want the effect to end. Thus you should end up with parallel lines that "contain" the effect.

That's not what I'm seeing at all. When I click on the screen, the effect of the filter goes from the pin marker all the way to the top of the image. The width of the "borders" of the filter don't really have any effect at all, the effect always runs from the pin marker to the top of the image.

Am I doing something wrong or is Martin's description inaccurate?