[dolphin] [Bug 500173] New: Spurious windows while generating HTML preview in Wayland

Sun Feb 16 09:52:06 GMT 2025

https://bugs.kde.org/show_bug.cgi?id=500173

            Bug ID: 500173
           Summary: Spurious windows while generating HTML preview in
                    Wayland
    Classification: Applications
           Product: dolphin
           Version: 24.12.2
          Platform: Arch Linux
                OS: Linux
            Status: REPORTED
          Severity: normal
          Priority: NOR
         Component: general
          Assignee: dolphin-bugs-null at kde.org
          Reporter: kivanov1992 at gmail.com
                CC: kfm-devel at kde.org
  Target Milestone: ---

Created attachment 178429
  --> https://bugs.kde.org/attachment.cgi?id=178429&action=edit
Notice the Wayland icon appearing for a short time in the panel on the left,
and the preview flickering in the center

SUMMARY

When HTML file previews are generated in Dolphin under Wayland session, extra
windows briefly appear. These windows have the default Wayland icon, no
decorations, and contain the preview itself. They windows grab focus so using
anything is nearly impossible when many previews are generated at once. This
only happens in Wayland session, everything's fine in Xorg. It doesn't happen
to other file types as far as I've noticed (tried text or images).

STEPS TO REPRODUCE
(I include the commands I ran in the Dolphin's terminal, but it can be
reproduced in other ways, for instance, when you already have a folder with
many html files such as a local website mirror)
1. Clear thumbnails cache (rm -r ~/.cache/thumbnails/)
2. Make an empty directory at least one step deep (mkdir -p test/html)
3. Create some basic html files in it (for i in {1..10}; do echo
"<body>Test</body>" > test/html/test$i.html; done)
4. Open directory ./test/html/ or even ./test/ in Dolphin (cd test/html)

OBSERVED RESULT
Several windows containing rendered html appear in the middle of the screen and
grab focus.

EXPECTED RESULT
Previews should be generated in the background without popping up extra
windows.

SOFTWARE/OS VERSIONS
Operating System: EndeavourOS 
KDE Plasma Version: 6.3.0
KDE Frameworks Version: 6.10.0
Qt Version: 6.8.2
Kernel Version: 6.13.2-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 4 × Intel® Core™ i5-2520M CPU @ 2.50GHz
Memory: 7.6 GiB of RAM
Graphics Processor: Mesa Intel® HD Graphics 3000

ADDITIONAL INFORMATION

I assume that this has something to do with how the preview plugin works, and
it is actually made by Konqueror, and they use QWebEngineView (I base my
conclusions on searching sources for "thumbcreator html" in GitHub, and I'm by
no means a specialist). The closest I've come to pinpointing the bug is
somewhere inside the function KIO::ThumbnailResult WebArchiveCreator::create
(https://github.com/KDE/konqueror/blob/56c8860135e64a04235fc44bb609408847c0ca2c/plugins/webarchiver/thumbnailer/webarchivecreator.cpp#L91).
Maybe it's rather a Qt's roblem and not KDE's, but I have no skills to
determine that :(

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