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https://issues.apache.org/jira/browse/JSPWIKI-1322?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18137420#comment-18137420
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Arturo Bernal commented on JSPWIKI-1322:
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[~weberjn], I could reproduce this on master (3.0.1-git-3) in Chromium. On a
reload with the files cached, the page is painted after about 70 to 110 ms with
the content under the header, and about half a second later the content moves
down by the height of the header (106 px at 1327 px wide, 69 px at 500 px
wide); the layout shift measured by the browser was 0.41 to 0.44 at 1327 px and
0.83 at 500 px. On the first load, without cache, I measured no such shift.
The header is position: fixed, so it takes no space, and the script of the yoyo
effect added a spacer of its height after the page had loaded. Pull request
https://github.com/apache/jspwiki/pull/576 makes the header sticky so that it
keeps its space from the first paint, and removes the spacer. With it, the
content does not move on reload at 1327, 1000, 800 and 500 px wide; a smaller
shift of the footer (0.046 to 0.082) remains, which has another cause I did not
look into. Hiding the header when scrolling down and showing it when scrolling
up behaves the same as before in my measurements.
I have not tested Firefox or Edge, where you saw it. Could you try the branch
bug/JSPWIKI-1322 of https://github.com/arturobernalg/jspwiki (or a build of
that pull request) in your browsers and tell me whether the page still flashes
on reload?
> Page flashing on reload
> -----------------------
>
> Key: JSPWIKI-1322
> URL: https://issues.apache.org/jira/browse/JSPWIKI-1322
> Project: JSPWiki
> Issue Type: Bug
> Components: Templates and UI
> Affects Versions: 3.0.0
> Reporter: Jürgen Weber
> Priority: Major
> Labels: pull-request-available
> Attachments: 2026-11-03 17_20_18-Wiki-Screenshot.jpg
>
>
> On reloading the browser page, the main content is pulled upwards and goes
> down again, this results in the page flashing.
> This annoys our users.
> Continually reloading allows to screenshot this, see attachment.
> This is in 3.0.0 release and current master3. Reproduced in Firefox and Edge.
>
> Maybe related to JSPWIKI-9 ?
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