Emacs was changed from one window into 3 windows after typing C-c C-c
C-c on the heading. Note also some of the important text (tags) extends
into the window edge (I have truncate-lines defaults to t).

,----
| (setq-default truncate-lines t)
| (setq split-width-threshold 156
|       truncate-partial-width-windows nil)
`----

Now if the frame is not in fullscreen it only pops up a tag selection
window after pressing C-c C-c C-c, which is like this: