Constrain an existing line

Using "line" or "polyline" to make a rectangular object, it was needed to make it crooked, some sides not perfectly vertical or horizontal, or, produced from a "center line trace" from a bitmap image that was tilted.   Now I want to reposition those lines in order to make them vertical and/or horizontal, using the shape tool.   What I use to do is drag some H or V guidelines where I want to drag the lines, and using shape tool grab and pull the nodes to the guidelines, considering "snap to guidelines" is set.  Is there any other easier way to fix that?  Thanks.