Hello. This feature request is best explained by example. I have a text file, see below:

    THE PROJECT                                   THE FOUNDATION

In the begining                         An independent non-profit .......
  The project .... [terse edited text   ........ and we .........
  with /emphasizes/ and references
  to wikipedia.]

Now                                     MEMBERSHIP
  .......... [edited text to mention      The membership ..... [terse edited
  reports]                                text about membership]
     Report 1...                              Membership 1
     Report 2...                              Membership 2
     Report 3...                              Membership 3
                                              Membership 4
WE BELIEVE IN                                 Membership 5
  Freedom and community
    [Even terser edited text with       FINANCE
     references to the GNU project.]      [a short explanation how GNOME
  Collaboration and meritocracy           foundation is financed and list of
    [terse edited text that emphasises    financial reports.]
    digits, numeric facts and links to
    get-involved section]               LEGAL Information
  People-centered                         [A list of references to legal
    [Lorem ipsum dolor sit amet,          documents.]
    consectetur adipisicing elit] 

You can see the text file is formatted using spaces. Only in "overtype mode" can such a text file be edited, but even though it's not convenient. Suppose I want to remove "Membership 5" and let every other line in the right column move upward one line, it must be hell of trouble to do it. A easy way is to add a feature to select a rectangle in the text file, and the editing area is in the rectangle. If I select the whole right column in a rectangle, then, editing only affects characters in that area. Removing a line, for example, makes every below other line lifts up in the rectangle, but outside does not move. Perhaps this feature isn't used much, but having this feature created a new way of doing text editing, people may find interesting ways to use text editor as a mind-map, an organizational-chart editor and a web layout editor without having to use a graphical tool, and being able to send charts through emails. This may be further enhanced with the use of box-drawing characters. Any thoughts?