The Grab Line function is used to pick up and move the entire body of one line segment, along with any free pads, vias, and other vertices coincident with the line segment's end-points.
To grab a line segment, you must first position the cursor somewhere within the interior of the desired line segment and then press <left mouse> or <Enter>.
In the event of multiple targets, lines on the current layer are given preference over those on other layers, and shorter lines are given preference over longer ones.
To grab lines that are part of a component, the current active layer must be set to the same layer as the line that is to be grabbed.