I always wanted to have a text editor capable of writing several columns of text side by side. This way, I could have a large file split into several columns with easy visualization. Editors like vim can split the screen vertically, but they're not great at keeping these columns in sync for the same file. This could be similar to the text flow option you'd find in desktop publishing software.
https://www.gnu.org/software/emacs/manual/html_node/emacs/Fo...