Editor to select text that is inside a rectangle

You can select a rectangular area to cut/copy in Visual Studio be pressing the Alt key prior to making your selection with the mouse or (Shift +) cursor keys. See How to: Select and Change Text.

The Zeus editor can do keyboard driven column cut/copy and paste.

Also the default Zeus mouse marking is in column mode.

If you use Vim, Ctrl + V will let you select a rectangular block of text.

The documentation says Ctrl + Q will let you do a rectangular select in mswin compatibility.