After I type "o" it used to look like:
+-----------------------------------------+
| Dired buffer |
| ...>file #1 |
| ... file #2 |
| ... file #3 |
| ... file #4 |
| |
+-----------------------------------------+
| This window now displays the contents |
| of file #1. |
| |
| |
| |
| |
+-----------------------------------------+
BUT NOW it looks like:
+--------------------+--------------------+
| Dired buffer | This window now |
| ...>file #1 | displays the |
| ... file #2 | contents of |
| ... file #3 | file #1. |
| ... file #4 | |
| | |
+--------------------+--------------------+
| |
| |
| |
| |
| |
| |
+-----------------------------------------+