New thumbnails are missing from file chooser

[Jeremy Bícha]

Impact
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Thumbnails do not show in the file chooser (provided by gtk4 which is also used by even non-GTK3 apps if they use xdg-desktop-portal-gnome) until the thumbnail is generated by for instance, viewing the folder in Nautilus.

This bug is new to Ubuntu 23.04 because GTK 4.10 is the first stable GTK release to support the "grid view" in the filechooser.

Test Case
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1. Use Firefox to download an image file. (This test case assumes you're using the default Firefox distributed as a Snap).
2. In Firefox, use the keyboard shortcut Ctrl+O to open the file chooser.
3. Navigate to where the file was downloaded (your Downloads/ folder?)
4. The file should show a thumbnail image

Number 4 doesn't happen correctly until you open the folder in Nautilus at least once.

Other Info
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I am linking to what upstream considers the master bug for this issue. But a duplicate of the issue is https://gitlab.gnome.org/GNOME/gtk/-/issues/5663 which has a clearer summary.

[Guillaume Michaud (gfmichaud)]

I've noticed it on 23.10 too.
I think that the file picker does not GENERATE thumbnails.
If thumbnails are generated beforehands by Nautilus, they get displayed.

[Guillaume Michaud (gfmichaud)]

Just found this thread on the issue:
https://discussion.fedoraproject.org/t/problem-with-new-file-picker-thumbnails-are-not-loaded/80073

[vadim (vadim1337)]

Watching by the forum, as someone proposes a solution, they say it sucks and do nothing. That's the whole point of open source.