When using dynamic lighting, I use those lines to block vision/movement and offset the lines half way into the wall tiles so that the wall textures can be seen. When I have a secret door on a map, I hide it as a normal wall and use my normal dynamic lighting lines to complete the misdirection. Once the party discovers the secret door, I delete the wall tile and move a door tile from another layer. Because many of my doors reside along the edge of my tile squares, I need to 'remap' the dynamic lighting lines to follow through the new position of the door as opposed to going through the center of the wall tile. It would be extremely handy to be able to move such 'remapped' lines from the GM's layer to the dynamic lighting layer.
