[BUG] %val{window_range} isn't working as expected

[caksoylar]

Version of Kakoune

v2023.08.05-95-g1da8952e

Reproducer

Create a long text file:

> seq 100 >100.txt

Repro script:

> cat <<EOF >test_window_range.kak
echo -debug "window_height: %val{window_height}"
echo -debug "scroll_window before: %val{window_range}"
execute-keys <c-f>
echo -debug "scroll_window after:  %val{window_range}"
buffer *debug*
EOF

Run script:

> kak -n -e 'source test_window_range.kak' 100.txt

Outcome

*** This is the debug buffer, where debug info will be written ***
window_height: 32
scroll_window before: 0 0 0 0
scroll_window after:  0 0 0 0

Expectations

*** This is the debug buffer, where debug info will be written ***
window_height: 32
scroll_window before: 0 0 32 0
scroll_window after:  30 0 32 0

Additional information

Might be related to #4975 , since reverting 9787756 on top of tested HEAD 1da8952 returns the expected result.

Not sure what operations exactly lead to incorrect results, but at least <c-f> in the repro above, gj and vj all seem to give the wrong result.

For context, I noticed the issue because it breaks my plugin kakoune-smooth-scroll. It depends on executing a given key in a draft context and checking whether the window_range changed before and after it to determine whether there was a window scroll.

[caksoylar]

It seems like the window_range update can be forced via a <c-l>, but that doesn't seem to work in a draft context (which is what the plugin currently does). Does anyone have a recommendation of how else I could detect a window range change resulting from an action, without actually performing the action on a non-draft client?

[sidkshatriya]

*** This is the debug buffer, where debug info will be written ***
window_height: 26
scroll_window before: 0 0 1552 0
scroll_window after:  0 0 1552 0

I can reproduce this error with kakoune on a42aa1e .

[krobelus]

yes it's #4975
there is some more commentary but no conclusion on #4994