Del and Delcol refuse unsaved text once, as acme's do

acme's Del asks winclean first and Delcol colclean (exec.c del, delcol):
unsaved text is warned about, and the same word again closes. pardes closed
at once. Both now refuse once through the one-warning-per-word mechanism
Exit uses, from keys, tags, exec and ctl alike. A pane dirty only by a
rename, or an empty one that never held a file, has no text to lose and is
not asked about, and a scratch or a command's output under 100 bytes is not
either, as acme's winclean passes a small unnamed window.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 6 insertions, 1 deletions

diff --git a/docs/tags.md b/docs/tags.md
index e6ec0585..f622520f 100644
--- a/docs/tags.md
+++ b/docs/tags.md
@@ -60,7 +60,12 @@ to its `ctl`, they step the body back and forward through its edits, as the
 `u` and `U` keys do. They are not in the default tags.
 
 `Del` closes a pane and gives its rows to one neighbor; the rest of the
-column keeps its heights. `Del k` (or `DelAbove`) gives them to the nearest
+column keeps its heights. A pane with unsaved text is refused once, as
+acme's Del warns (exec.c del, wind.c winclean): `<name>: Modified (Del again
+to discard)`, and the same `Del` again, nothing edited since, closes it and
+throws the text away; `Delcol` refuses a column holding such a pane the same
+way (exec.c delcol). Each word warns on its own, from a key, a tag, `exec`
+or a ctl, where the refusal fails the write with EIO. `Del k` (or `DelAbove`) gives them to the nearest
 expanded pane above, `Del j` (or `DelBelow`) to the one below, each falling
 back to the other side. Bare `Del` from the keyboard (`SPC d`, or Enter on
 the word) on a pane with expanded panes both above and below asks on the