Arch Linux

Does
sudo gtk-update-icon-cache -tf /usr/share/icons/hicolor
fix this problem?

Hmm, It does fix the problem.

I wonder why the hooks didn't cover this? Or perhaps something was just corrupt on my end...?

It is strange, but I see all icons and have no "ERROR: gui.application: Mypaint can't run sensibly without its icons; please check your installation" message.

> Icon search path: ['/home/earnest/local/data/icons', '/home/earnest

could you please revert XDG variables or try to run it from another (clean) user environment?

How would that help though? Running gtk-update-icon-cache previously already fixed the issue.

Regardless here is a shell session also demonstrating two other bugs in mypaint as it doesn't create preceeding directories, finally working as normal:

===

% unset XDG_CACHE_HOME XDG_CONFIG_HOME XDG_DATA_HOME

% mypaint
INFO: mypaint: Installation layout: conventional POSIX-like structure with prefix u'/usr'
INFO: lib.i18n: POSIX: LANG='en_GB.UTF-8'
INFO: lib.i18n: POSIX: LANGUAGE=None

** (mypaint:22100): WARNING **: Error retrieving accessibility bus address: org.freedesktop.DBus.Error.ServiceUnknown: The name org.a11y.Bus was not provided by any .service files
Traceback (most recent call last):
File "/usr/bin/mypaint", line 462, in <module>
main.main(datapath, iconspath, old_confpath, version=version)
File "/usr/share/mypaint/gui/main.py", line 225, in main
run()
File "/usr/share/mypaint/gui/main.py", line 202, in run
fullscreen = options.fullscreen,
File "/usr/share/mypaint/gui/application.py", line 223, in __init__
os.mkdir(basedir)
OSError: [Errno 2] No such file or directory: '/home/earnest/.config/mypaint'
zsh: exit 1 mypaint

% mkdir .config
mkdir: created directory '.config'

% mypaint
INFO: mypaint: Installation layout: conventional POSIX-like structure with prefix u'/usr'
INFO: lib.i18n: POSIX: LANG='en_GB.UTF-8'
INFO: lib.i18n: POSIX: LANGUAGE=None

** (mypaint:22198): WARNING **: Error retrieving accessibility bus address: org.freedesktop.DBus.Error.ServiceUnknown: The name org.a11y.Bus was not provided by any .service files
INFO: gui.application: Created basedir u'/home/earnest/.config/mypaint'
Traceback (most recent call last):
File "/usr/bin/mypaint", line 462, in <module>
main.main(datapath, iconspath, old_confpath, version=version)
File "/usr/share/mypaint/gui/main.py", line 225, in main
run()
File "/usr/share/mypaint/gui/main.py", line 202, in run
fullscreen = options.fullscreen,
File "/usr/share/mypaint/gui/application.py", line 223, in __init__
os.mkdir(basedir)
OSError: [Errno 2] No such file or directory: '/home/earnest/.local/share/mypaint'
zsh: exit 1 mypaint

% mkdir .local/share
mkdir: created directory '.local'
mkdir: created directory '.local/share'

% mypaint
INFO: mypaint: Installation layout: conventional POSIX-like structure with prefix u'/usr'
INFO: lib.i18n: POSIX: LANG='en_GB.UTF-8'
INFO: lib.i18n: POSIX: LANGUAGE=None

** (mypaint:22250): WARNING **: Error retrieving accessibility bus address: org.freedesktop.DBus.Error.ServiceUnknown: The name org.a11y.Bus was not provided by any .service files
INFO: gui.application: Created basedir u'/home/earnest/.local/share/mypaint'
INFO: gui.application: Created data subdir u'/home/earnest/.local/share/mypaint/backgrounds'
INFO: gui.application: Created data subdir u'/home/earnest/.local/share/mypaint/brushes'
INFO: gui.application: Created data subdir u'/home/earnest/.local/share/mypaint/scratchpads'
INFO: gui.brushmanager: Merging upstream brush changes into your collection.
INFO: gui.device: New device 'USB Keyboard' (GDK_SOURCE_MOUSE, axes:4, class=X11DeviceXI2, vendor='04d9', product='a0cd')
INFO: gui.device: New device 'TPPS/2 IBM TrackPoint' (GDK_SOURCE_TRACKPOINT, axes:2, class=X11DeviceXI2, vendor='0002', product='000a')
INFO: gui.device: New device 'Virtual core XTEST pointer' (GDK_SOURCE_MOUSE, axes:2, class=X11DeviceXI2, vendor=None, product=None)
INFO: gui.document: Initialized background from u'/usr/share/mypaint/backgrounds/10_soft_yellow.png'
WARNING: gui.keyboard: Ignoring keybinding for '<Actions>/BrushModifierActions/BlendModeMenu'

(mypaint:22250): Gtk-WARNING **: Theme parsing error: <data>:5:50: The style property GtkMenuBar:internal-padding is deprecated and shouldn't be used anymore. It will be removed in a future version
WARNING: gui.accelmap: Not listing '<Actions>/DocumentActions/RotateLeft' (no tooltip, fix before release!)
WARNING: gui.accelmap: Not listing '<Actions>/DocumentActions/RotateRight' (no tooltip, fix before release!)
/usr/lib/python2.7/site-packages/pygtkcompat/pygtkcompat.py:180: TypeError: Passing arguments to gi.types.Boxed.__init__() is deprecated. All arguments passed will be ignored.
rect = Gdk.Rectangle(0, 0, 0, 0)
INFO: lib.document: save_ora: u'/home/earnest/.local/share/mypaint/scratchpads/.tmpsave.autosave.ora' (None, {'feedback_cb': <function gtk_main_tick at 0x7f57447965f0>, 'save_srgb_chunks': True})
INFO: lib.document: 0.085s save_ora total
INFO: gui.filehandling: Saved to u'/home/earnest/.local/share/mypaint/scratchpads/autosave.ora'

I looked into /usr/lib/pacman/hooks/gtk-update-icon-cache

while read -r f; do
if [[ -e ${f}index.theme ]]; then
gtk-update-icon-cache -q "$f"
elif [[ -d $f ]]; then
rm -f "${f}icon-theme.cache"
rmdir --ignore-fail-on-non-empty "$f"
fi
done

it looks like it does not call gtk-update-icon-cache if there was no /usr/share/icons/.../index.theme

My be it is missing dependency on hicolor-icon-theme package.

I've added hicolor-icon-theme to deps, so it should not happen anymore.