[Pkg-lxde-maintainers] Bug#906288: openbox-lxde-session: /usr/bin/startlxde overrides XDG_DATA_DIRS making all local .desktop files unable to show on menu

[(Holloway), Chew Kean Ho]

Package: openbox-lxde-session
Version: 0.99.2-3
Severity: normal

Dear Maintainer,

   * What led up to the situation?
When I install snaps in a freshly installed Debian 9 with LXDE. The
snaps with .desktop should be populated automatically inside the menu,
but it didn't.

   * What exactly did you do (or not do) that was effective (or
     ineffective)?
After thorough investigation (logged in
https://forum.snapcraft.io/t/snaps-not-appearing-in-debian9-stretch-lxde-menu-not-wayland-bug/6866/14),

I discovered the /usr/bin/lxde has this line overrides all the
XDG_DATA_DIRS set by Xsession.d configuration files:
```
export
XDG_DATA_DIRS="/usr/local/share/:/usr/share/:/usr/share/gdm/:/var/lib/menu-xdg/"
```

By replacing that line with a proper checking before overwriting, the
issue disappeared and all the custom paths appears in the menu properly.
```
xdg_path="/usr/local/share/:/usr/share/:/usr/share/gdm/:/var/lib/menu-xdg/"
if [ -z "$XDG_DATA_DIRS" ]; then
        export XDG_DATA_DIRS="$xdg_path"
else
	if [ -z "$(echo "$XDG_DATA_DIRS" | grep "$xdg_path")" ]; then
		export XDG_DATA_DIRS="${XDG_DATA_DIRS}:$xdg_path"
	fi
fi
unset xdg_path
```

   * What was the outcome of this action?
All custom .desktop path are properly populated without manual
intervention.

   * What outcome did you expect instead?
I expect all the .desktop are populated properly, without monkey
patching anything created by the package.

Currently, those UI-based snaps are quite hard to access, but not
impossible.

   * p/s
I'm too new to debian mailing list and reportbug tool. In case of
silence, please reach me at kean.ho.chew at zoralab.com. I'm willing
to help.


-- System Information:
Debian Release: 9.5
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.9.0-7-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages openbox-lxde-session depends on:
ii  lxde-common  0.99.2-3
ii  lxsession    0.5.3-2
ii  openbox      3.6.1-4

openbox-lxde-session recommends no packages.

openbox-lxde-session suggests no packages.

-- no debconf information