Light a held column grip, and rail its landing beside the rule where the GUI shows it

The column grip worked in the GUI but showed nothing anyone could see.
Driving the real SDL window with pixel mouse events, press, drag and
release all reach the core and reorder or resize the column; the feedback
is what failed. The grip kept its muted color while held, and a reorder's
insertion rail was drawn in the gutter cell at the destination edge. The
GUI paints that cell as the column's scroll rail, and at the window's left
edge, the common case of moving the right column first, the dashes were
lost in it. From the leftmost column, a drag short of a neighbour's middle
shows no rail, rightly, since nothing would move, but nothing said the
grip was even held.

A held grip now lights in column_box, the accent its muted color is mixed
from, and the rail takes that color. The rail runs in the seam cell left of
where the column's rule will land, where a border drag's rail runs, for a
reorder and a left-edge move alike; at the window's left edge, which has no
seam, it runs just past the scroll rail, leaving column 0's grip and pane
boxes whole. A carried column's pointer aims at a place, not a word, so the
column tags no longer light the word under it, and a release snaps the
layout as a border drag's does rather than animating it. The preview and the release both
ask layout.columnDrop where the column goes, so the rail stands where the
release puts the edge, and the drag no longer carries its unused column
index.

The GUI test feed takes ESC]777;mouse;<down|up|motion>;<button>;<x>;<y> in
window pixels and dispatches it as an SDL event. test/column_grip.py uses
it to drive the grip through the same pixel-to-cell and tag hit path as a
hand on the mouse, and checks the grip, the rail and the result against
GPU captures and the 9P grid.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

2 files changed, 205 insertions, 0 deletions

diff --git a/test/snapshots/colgrip.golden b/test/snapshots/colgrip.golden
new file mode 100644
index 00000000..e096a665
--- /dev/null
+++ b/test/snapshots/colgrip.golden
@@ -0,0 +1,170 @@
+== style rest grid=100x24
+|0: 0-70 #b2c3b8,#1d2824, 71-99 d,#1d2824,
+|1: 0-1 #ffffff,#887455, 2-2 d,#1d2824, 3-34 #b2c3b8,#1d2824, 35-49 d,#1d2824, 50-51 #ffffff,#887455, 52-52 d,#26362d, 53-84 #becfc4,#26362d, 85-99 d,#26362d,
+|2: 0-1 #ffffff,#496656, 2-2 d,#1d2824, 3-31 #b2c3b8,#1d2824, 32-36 #d3b0d9,#1d2824, 37-49 #b2c3b8,#1d2824, 50-51 #000000,#add38a, 52-52 d,#26362d, 53-81 #becfc4,#26362d, 82-84 #dfbce5,#26362d, 85-99 #becfc4,#26362d,
+|3: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-7 #e5eee5,#0d1410, 8-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|4: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|5: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-99 d,#0d1410,
+|6: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|7: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|8: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|9: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|10: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|11: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|12: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|13: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|14: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|15: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|16: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|17: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|18: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|19: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|20: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|21: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|22: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|23: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+== style held grid=100x24
+|1: 0-1 #ffffff,#887455, 2-2 d,#1d2824, 3-34 #b2c3b8,#1d2824, 35-49 d,#1d2824, 50-51 #000000,#f4c086, 52-52 d,#26362d, 53-84 #becfc4,#26362d, 85-99 d,#26362d,
+== snap resize-drag grid=100x24 cursor=54,5
+|Newcol Joincol Find Grep Help Changelog Tutor Dump NextColor Debug Kill
+|   New Tty Find Grep Joincol Delcol    ╎             New Tty Find Grep Joincol Delcol
+|   /tmp/pardes-snap/colgrip/cwd/w.txt S╎ve Tty Col   /tmp/pardes-snap/colgrip/cwd Tty Save Mode Filt
+|     1 x                               ╎            ls
+|                                       ╎            w.txt
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+|                                       ╎
+== style resize-drag grid=100x24
+|1: 0-1 #ffffff,#887455, 2-2 d,#1d2824, 3-34 #b2c3b8,#1d2824, 35-38 d,#1d2824, 39-39 #f4c086,#1d2824, 40-49 d,#1d2824, 50-51 #000000,#f4c086, 52-52 d,#26362d, 53-84 #becfc4,#26362d, 85-99 d,#26362d,
+|2: 0-1 #ffffff,#496656, 2-2 d,#1d2824, 3-31 #b2c3b8,#1d2824, 32-36 #d3b0d9,#1d2824, 37-38 #b2c3b8,#1d2824, 39-39 #f4c086,#1d2824, 40-49 #b2c3b8,#1d2824, 50-51 #000000,#add38a, 52-52 d,#26362d, 53-81 #becfc4,#26362d, 82-84 #dfbce5,#26362d, 85-99 #becfc4,#26362d,
+|3: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-7 #e5eee5,#0d1410, 8-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|4: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|5: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-99 d,#0d1410,
+|6: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|7: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|8: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|9: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|10: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|11: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|12: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|13: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|14: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|15: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|16: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|17: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|18: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|19: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|20: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|21: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|22: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+|23: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-38 d,#0d1410, 39-39 #f4c086,#0d1410, 40-49 d,#0d1410, 50-50 d,#608269, 51-51 d,#0d1410, 52-99 #e5eee5,#0d1410,
+== snap resize-done grid=100x24 cursor=44,5
+|1:    New Tty Find Grep Joincol Delcol        New Tty Find Grep Joincol Delcol
+|2:    /tmp/pardes-snap/colgrip/cwd/w.txt Sa   /tmp/pardes-snap/colgrip/cwd Tty Save Mode Filter Collaps
+|3:      1 x                                  ls
+|4:                                           w.txt
+|5:
+|6:
+|7:
+|8:
+|9:
+|10:
+|11:
+|12:
+|13:
+|14:
+|15:
+|16:
+|17:
+|18:
+|19:
+|20:
+|21:
+|22:
+|23:
+== snap reorder-drag grid=100x24 cursor=44,5
+|3:  ╎   1 x                                  ls
+|4:  ╎                                        w.txt
+|5:  ╎
+|6:  ╎
+|7:  ╎
+|8:  ╎
+|9:  ╎
+|10:  ╎
+|11:  ╎
+|12:  ╎
+|13:  ╎
+|14:  ╎
+|15:  ╎
+|16:  ╎
+|17:  ╎
+|18:  ╎
+|19:  ╎
+|20:  ╎
+|21:  ╎
+|22:  ╎
+|23:  ╎
+== style reorder-drag grid=100x24
+|1: 0-1 #ffffff,#887455, 2-2 d,#1d2824, 3-34 #b2c3b8,#1d2824, 35-39 d,#1d2824, 40-41 #000000,#f4c086, 42-42 d,#26362d, 43-74 #becfc4,#26362d, 75-99 d,#26362d,
+|2: 0-1 #ffffff,#496656, 2-2 d,#1d2824, 3-31 #b2c3b8,#1d2824, 32-36 #d3b0d9,#1d2824, 37-39 #b2c3b8,#1d2824, 40-41 #000000,#add38a, 42-42 d,#26362d, 43-71 #becfc4,#26362d, 72-74 #dfbce5,#26362d, 75-99 #becfc4,#26362d,
+|3: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-7 #e5eee5,#0d1410, 8-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|4: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|5: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-99 d,#0d1410,
+|6: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|7: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|8: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|9: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|10: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|11: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|12: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|13: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|14: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|15: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|16: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|17: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|18: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|19: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|20: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|21: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|22: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+|23: 0-0 d,#608269, 1-1 #f4c086,#0d1410, 2-6 #59675c,#0d1410, 7-39 d,#0d1410, 40-40 d,#608269, 41-41 d,#0d1410, 42-99 #e5eee5,#0d1410,
+== snap reorder-done grid=100x24 cursor=4,5
+|1:    New Tty Find Grep Joincol Delcol                            New Tty Find Grep Joincol Delcol
+|2:    /tmp/pardes-snap/colgrip/cwd Tty Save Mode Filter Collaps   /tmp/pardes-snap/colgrip/cwd/w.txt Sa
+|3:   ls                                                             1 x
+|4:   w.txt
+|5:
+|6:
+|7:
+|8:
+|9:
+|10:
+|11:
+|12:
+|13:
+|14:
+|15:
+|16:
+|17:
+|18:
+|19:
+|20:
+|21:
+|22:
+|23:
diff --git a/test/snapshots/colgrip.snap b/test/snapshots/colgrip.snap
new file mode 100644
index 00000000..c2b403ed
--- /dev/null
+++ b/test/snapshots/colgrip.snap
@@ -0,0 +1,35 @@
+# Column grips: the two cells left of a column tag carry the column. A grabbed
+# grip lights, and a rail in its color stands where the column will land.
+# The right column is at x 50; its grip is cells 51-52 (1-based) on row 2.
+file w.txt x
+start 24 100 w.txt
+wait 8000 Newcol Joincol
+wait 8000 w.txt
+stable 700 20000
+key a-n
+key a-c
+stable 700 15000
+snapstyle rest
+# held on its own grip: lit, and no rail, since it lands where it is
+press left 51 2
+stable 400 5000
+snapstyle held
+# dropped short of the left column's middle, the left edge moves: the rail is
+# in the seam cell left of where the column's rule will be
+drag left 41 2
+stable 400 5000
+snap resize-drag
+snapstyle resize-drag
+release left 41 2
+stable 700 15000
+snap resize-done
+# carried over the left column's left half it goes first; the window edge
+# has no seam, so the rail runs in the gutter's last cell
+press left 41 2
+drag left 10 2
+stable 400 5000
+snap reorder-drag
+snapstyle reorder-drag
+release left 10 2
+stable 700 15000
+snap reorder-done