# every pane open splits ONE existing pane, the rest of the column keeps its
# sizes: Alt-n splits the active pane, an execute-spawned command pane for a file's
# dir splits only the bottom pane of the rightmost column. At this narrow
# width the first looked-up file also splits below its source, leaving every
# unrelated pane (including the ones above the source) at its exact rectangle.
dirmk sub
file sub/f.txt echo 'TTY'OK
start 31 100 -n 3
wait 8000 sub
stable 700 20000
# give pane 0 (top-left) some content so its content-height split is visible
press left 5 9
release left 5 9
stable 400 5000
key i
text echo one; echo two
key enter
key esc
settle 100
stable 400 5000
snap before
# Alt-n: new shell below pane 0 — the bottom pane's boundary must not move
key a-n
stable 700 15000
snap altn-left
# make the right column two panes (Alt-n in a fresh column, trivial split)
press left 70 9
release left 70 9
stable 400 5000
key a-n
stable 700 15000
snap altn-right
# look sub/f.txt from the bottom-left shell: the first doc splits this shell,
# not the top-left pane. Both panes above it and the entire right column stay put.
press left 5 28
release left 5 28
stable 400 5000
key i
text sub/f.txt
key esc
settle 100
stable 400 5000
press right 7 28
release right 7 28
stable 700 15000
snap file-open
# execute the file's command (middle drag over line 1): it runs as a command
# pane for sub/, forked at the bottom of the rightmost column, splitting only
# the pane above it
press middle 8 25
drag middle 19 25
release middle 19 25
wait 10000 TTYOK
motion 40 27
stable 700 10000
snap ttydir