Hi again, another video attempt at a post.
We need to pay close attention to the "focus" of Revit when we enter a value on the Options Bar. In the video example I show a roof in the sketch process and I want to use the Offset parameter to create the roof edge 2'-0" from the exterior wall. When I enter the value and then try to use the Tab key to "Select the Chain of Walls or Lines" Revit doesn't acknowledge the walls. It just moves the "focus" between the Offset parameter and the Extend to Wall Core options. When I click in the Drawing Window the focus moves away from the Options Bar and the TAB key feature will work.
This is just a subtle thing that can be frustrating if you don't notice what it happening on the Options Bar. I hope the video helps too!