[vim/vim] Flickering in popups windows - Introduced by patch 9.2.0016 (Issue #19510)

Javier Jaramago Fernández

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Feb 25, 2026, 10:53:11 AM (6 days ago) Feb 25

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JavierJF created an issue (vim/vim#19510)

Steps to reproduce

Copy the following script in a buffer.

" scroll_popup.vim
" Continuously scrolling popup with multi-line content

let s:text = []
for i in range(1, 50)
	call add(s:text, printf("This is scrolling line %02d — Vim popup demo", i))
endfor

let s:firstline = 1
let s:popup_id = -1

function! s:scroll_popup(timer) abort
	let s:firstline += 1

	" Wrap when reaching the end
	if s:firstline > len(s:text)
		let s:firstline = 1
	endif

	call popup_setoptions(s:popup_id, {'firstline': s:firstline})
endfunction

function! StartScrollingPopup() abort
	let s:popup_id = popup_create(s:text, {
		\ 'title': 'Scrolling Popup',
		\ 'pos': 'center',
		\ 'minwidth': 60,
		\ 'minheight': 10,
		\ 'maxheight': 10,
		\ 'border': [],
		\ 'scrollbar': 1,
		\ 'opacity': 100,
	\ })

	" Scroll every 500 ms
	call timer_start(1000, function('s:scroll_popup'), {'repeat': -1})
endfunction

call StartScrollingPopup()

Source the buffer. If there is background text overlapping with the popup, flickering will start to take place in the areas where background text intersect with popup text.

The issue has been bisected to patch 9.2.0016, with commit 6c20307 and subsequent commit 95e8faa. This is reproducible in at least alacritty and kitty terminal emulators.

Expected behaviour

There should be no flickering when the popup is scrolled or refreshed.

Version of Vim

Bisected to patch 9.2.0016

Environment

Operating system: Arch Linux
Terminal: Alacritty / Kitty
$TERM: xterm-256color
Shell: zsh / bash

Logs and stack traces

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Mao-Yining

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Feb 25, 2026, 11:06:55 AM (6 days ago) Feb 25

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mao-yining left a comment (vim/vim#19510)

Is this relate to #19499 ?

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Javier Jaramago Fernández

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Feb 25, 2026, 11:15:51 AM (6 days ago) Feb 25

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JavierJF left a comment (vim/vim#19510)

@mao-yining I can't reproduce with your script in particular, it's likely to be the same issue. The fact that I can't reproduce may be because of the environment different or terminal difference. If you want to confirm if the issues are related you can compile VIM against 89712b9. If your script fails to reproduce with that version, is the same issue.

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Foxe Chen

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Feb 25, 2026, 6:43:57 PM (6 days ago) Feb 25

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64-bitman left a comment (vim/vim#19510)

I am also pretty sure I am experiencing this issue with the vim-fuzzbox plugin

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Shougo

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Feb 25, 2026, 7:14:14 PM (6 days ago) Feb 25

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Shougo left a comment (vim/vim#19510)

I think #19297 fixes the issue.

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Christian Brabandt

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Feb 26, 2026, 4:01:23 PM (5 days ago) Feb 26

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Closed #19510 as completed via 97c5bed.

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Yggdroot

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Mar 2, 2026, 10:04:07 PM (21 hours ago) Mar 2

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Yggdroot left a comment (vim/vim#19510)

This issue should not be closed, v9.2.0089 still has the issue.

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Shougo

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Mar 2, 2026, 10:23:11 PM (21 hours ago) Mar 2

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Shougo left a comment (vim/vim#19510)

Hi, I have tested above test_popup.vim, but the problem is fixed.
My version is Vim 9.2.0096. Please test the latest version.

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mattn

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12:22 AM (19 hours ago) 12:22 AM

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mattn left a comment (vim/vim#19510)

@Yggdroot could you please test #19559 ?

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Yggdroot

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12:53 AM (19 hours ago) 12:53 AM

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Yggdroot left a comment (vim/vim#19510)

Hi, I have tested above test_popup.vim, but the problem is fixed. My version is Vim 9.2.0096. Please test the latest version.

try the following reproduce:

function! ShowSimplePopup()
    call cursor(13, 1)
    let id = popup_create(
                \ ['Hello from popup!',
                \  'Hello from popup!',
                \  'Hello from popup!',
                \  'Hello from popup!',
                \  'Press q to close'],
                \ {
                \   'line': 10,
                \   'col': 20,
                \   'minwidth': 30,
                \   'maxheight': 5,
                \   'padding': [0,1,0,1],
                \   'border': [],
                \   'filter': 'PopupFilter'
                \ })
    call win_execute(id, 'setlocal cursorline')
endfunction

function! PopupFilter(id, key)
    if a:key ==# 'q'
        call popup_close(a:id)
        return 1
    elseif a:key ==# 'j'
        call win_execute(a:id, 'normal! j')
        return 1
    elseif a:key ==# 'k'
        call win_execute(a:id, 'normal! k')
        return 1
    endif
    return 0
endfunction

call ShowSimplePopup()

supose the file called a.vim,

vim a.vim
:so %
press j or k for some time.

The reproduce may not cover all the scenarios， because I find flicking both on Linux and Windows, but the script can only reproduce the issue on Windows.

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Yggdroot

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1:17 AM (18 hours ago) 1:17 AM

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Yggdroot left a comment (vim/vim#19510)

@Yggdroot could you please test #19559 ?

The PR does not fix the flickering issue.

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Shougo

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1:36 AM (18 hours ago) 1:36 AM

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Shougo left a comment (vim/vim#19510)

try the following reproduce:

Sorry. I cannot reproduce the problem with clean Vim environment.
Is this a problem that only occurs on Windows?

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Yggdroot

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1:41 AM (18 hours ago) 1:41 AM

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Yggdroot left a comment (vim/vim#19510)

try the following reproduce:

Sorry. I cannot reproduce the problem with clean Vim environment. Is this a problem that only occurs on Windows?

No. But I can only make a minimal reproduceable script on Windows.

Press j or k for 10 seconds.

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Linwei

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2:01 AM (18 hours ago) 2:01 AM

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skywind3000 left a comment (vim/vim#19510)

Sorry. I cannot reproduce the problem with clean Vim environment.

It is easy to reproduce in GVim:

gvim-flicker.gif (view on web)

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mattn

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2:02 AM (17 hours ago) 2:02 AM

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mattn left a comment (vim/vim#19510)

It is easy to reproduce in GVim (a popup window from Leaderf plugin):

Please provide small script to reproduce. If you can't provide way to reproduce easily, it's not EASY.

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Yggdroot

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2:19 AM (17 hours ago) 2:19 AM

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Yggdroot left a comment (vim/vim#19510)

It is easy to reproduce, just use my script above,

vim vim92/README.txt
:so a.vim
Press and hold the j key.

2.gif (view on web)

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mattn

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2:29 AM (17 hours ago) 2:29 AM

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mattn left a comment (vim/vim#19510)

https://github.com/user-attachments/assets/ac089e00-99e2-4220-963d-87f86ce7308a

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Yggdroot

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9:44 AM (10 hours ago) 9:44 AM

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Yggdroot left a comment (vim/vim#19510)

2026-03-03.162710.mp4

hold the j key.

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Linwei

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2:02 PM (5 hours ago) 2:02 PM

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skywind3000 left a comment (vim/vim#19510)

@mattn there is a flicker in your video between 00:02 - 00:03

2026-03-03.162710.mp4

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