A column can be empty, as acme's can; new panes go where acme's makenewwindow puts them

Newcol makes an empty column; closing a column's last pane leaves it empty with
the keyboard on its tag; Delcol and Joincol alone take a column away; the
session's last pane closing quits. The +New stand-in and replaceStillborn /
stillborn_joiner are gone. Every new pane goes through exec.placeNew, which
follows acme's makenewwindow (active column, empty column whole, blank space,
halving the biggest) or, with Placement pardes, the old rules. ColumnTags is
gone: column tags are always shown. A grip drag shows acme's box cursor.

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

1 files changed, 16 insertions, 0 deletions

diff --git a/src/CHANGELOG.md b/src/CHANGELOG.md
index f8451baf..874082d8 100644
--- a/src/CHANGELOG.md
+++ b/src/CHANGELOG.md
@@ -2,6 +2,22 @@
 
 ## 0.0.3
 
+- A column can be empty, as in acme. `Newcol` makes an empty column and
+  gives its tag the keyboard; closing a column's last pane, or dragging it
+  away, leaves the column where it was with nothing in it, drawn as its tag
+  over blank space. The `+New` placeholder that used to stand in an emptied
+  column, and the machinery that swapped it out when something else arrived,
+  are gone. Closing the session's last pane now quits.
+- New panes go where acme's makenewwindow puts them: into the active column
+  (the one last typed or clicked in), filling it when it is empty, else under
+  the text of a pane with room to spare, else halving the biggest pane; never
+  into a new column. `Placement pardes` brings back the old rules, which open a
+  first document in a column of its own.
+- Column tags are always shown: the `ColumnTags` setting is gone, and an
+  init file's `ColumnTags` line is ignored with a message.
+- Carrying a pane or a column by its grip shows acme's box cursor in the SDL
+  shell and a move cursor on the web.
+
 - `Del` takes a side. `Del k` and `DelAbove` give the closed pane's rows to
   the expanded pane above it, `Del j` and `DelBelow` to the one below. A bare
   `Del` from the keyboard on a pane with panes both above and below asks on