Icons of some installed apps (flatpaks) do not show up in home screen

[jjardon]

Describe the bug
Icons of some installed apps (flatpaks) do not show up home screen: only way to launch them is through the command line

To Reproduce

$ flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
$ flatpak install flathub com.github.flxzt.rnote

Application installs fine and you can run it with:

$ flatpak run com.github.flxzt.rnote

But application icon doesn't show up in the home screen.
Seems this is because the XDG_DATA_DIRS environment variable is not used to look to the location of the respective .desktop files.
(See workaround and possible root cause in the end of this bug report)

Expected behavior
Application icon should appear in the main screen

Desktop (please complete the following information):

• OS: JingOS 1.2.0

Smartphone (please complete the following information):

• Device: JingPad

Additional context
Current workaround:

• Copy the application desktop file from /var/lib/flatpak/exports/share/applications/ to ~/.local/share/applications/ (see Where are all the installed flatpak apps .desktop files located  flatpak/flatpak#1286 (comment) for a explanation)

Possible solution:

• After some investigation, seems the problem is in this commented code: https://github.com/JingOS-team/plasma-phone-components/blob/master/containments/homescreen/listmodelmanager.cpp#L107 and https://github.com/JingOS-team/plasma-phone-components/blob/master/containments/homescreen/listmodelmanager.cpp#L121 ; without those the .desktop files are not read in all the correct locations (the ones defined in the env variable XDG_DATA_DIRS