Since switching from my distro-provided GTK2-based Geeqie to the Flatpak-based GTK3 Geeqie, its taskbar entries have had no icons.
In case it's relevant to reproduce the problem, here's my OS loadout:
ssokolow@monolith ~ % lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.6 LTS
Release: 20.04
Codename: focal
ssokolow@monolith ~ % echo $XDG_CURRENT_DESKTOP
KDE
ssokolow@monolith ~ % flatpak --version
Flatpak 1.14.4
ssokolow@monolith ~ % flatpak info org.geeqie.Geeqie
[...]
Commit: b9404f99e3213137727341c40d13ce5da313915acdf025dcb1a3b18edebacded
Parent: 746ec7bcf4dfbc33f519a053e4b4af7fca5cdf68f24096e05961f1bbca8195b9
Subject: Update geeqie-1.7.3.tar.xz to 2.1 (#20) (b624c5a0)
Date: 2023-06-17 17:58:53 +0000
...and, while I can't confirm it will reproduce the problem (no time to check right now), you can get a ready-made Kubuntu 20.04 virtual machine image to test with here: https://www.osboxes.org/kubuntu/
Since switching from my distro-provided GTK2-based Geeqie to the Flatpak-based GTK3 Geeqie, its taskbar entries have had no icons.
In case it's relevant to reproduce the problem, here's my OS loadout:
...and, while I can't confirm it will reproduce the problem (no time to check right now), you can get a ready-made Kubuntu 20.04 virtual machine image to test with here: https://www.osboxes.org/kubuntu/