Understanding appindicator_tray.py

[sbradnick]

I'm working with eww and the newly added systray functionality. Keeping my expectations in check considering i3+eww (x11) probably isn't high on the support list and without getting too far into the weeds out of the gate, running python3 /usr/lib64/python3.11/site-packages/xpra/platform/posix/appindicator_tray.py appears completely functional. Is there a way to force that to be used? I'm not sure if the code is using GTKStatusIconTray no-matter-what at this point.

The eww log shows this entry when I run the appindicator_tray.py command: notifier_host::watcher > new item: :1.269/org/ayatana/NotificationItem/test

Thanks!

[totaam]

Yes, this needs to be explained, because choosing a backend is just really nasty.

First, there are two types of system trays.

Xpra's own menu

Configured using (--tray=yes|no)
It is handled in https://github.com/Xpra-org/xpra/blob/master/xpra/client/mixins/tray.py
The actual tray is instantiated here:

xpra/xpra/client/mixins/tray.py

Lines 122 to 123 in 08ce222

	tray = self.make_tray(XPRA_APP_ID, menu, self.get_tray_title(), tray_icon_filename,
	xpra_tray_geometry, xpra_tray_click, xpra_tray_mouseover, xpra_tray_exit)

Using the tray backends from:

xpra/xpra/client/mixins/tray.py

Lines 80 to 84 in 08ce222

	def get_tray_classes(self) -> list[type]:
	# subclasses may add their toolkit specific variants, if any
	# by overriding this method
	# use the native ones first:
	return get_native_tray_classes()

This method is overriden in the GTK client implementation to add Gtk.StatusIcon to the backend list:

xpra/xpra/client/gtk3/client_base.py

Lines 818 to 820 in 08ce222

	def get_tray_classes(self) -> list[type]:
	from xpra.client.mixins.tray import TrayClient
	return self._add_statusicon_tray(TrayClient.get_tray_classes(self))

Whether it goes first or last in the backend list of options is decided here:

xpra/xpra/client/gtk3/client_base.py

Lines 805 to 816 in 08ce222

	def _add_statusicon_tray(self, tray_classes: list[type]) -> list[type]:
	if not is_Wayland():
	try:
	from xpra.client.gtk3.statusicon_tray import GTKStatusIconTray
	# unlikely to work with gnome:
	if is_gnome() or WIN32 or OSX:
	tray_classes.append(GTKStatusIconTray)
	else:
	tray_classes.insert(0, GTKStatusIconTray)
	except Exception as e:
	log.warn("failed to load StatusIcon tray: %s" % e)
	return tray_classes

We don't use it all on Wayland, and it goes last in the list with gnome, macos and MS Windows.

system tray forwarding

Configured using --system-tray=yes|no
This is handled by the generic window forwarding code: https://github.com/Xpra-org/xpra/blob/master/xpra/client/mixins/windows.py
It follows a similar path:

xpra/xpra/client/mixins/windows.py

Lines 627 to 631 in 08ce222

	def make_system_tray(self, *args):
	""" tray used for application systray forwarding """
	tc = self.get_system_tray_classes()
	traylog("make_system_tray%s system tray classes=%s", args, tc)
	return make_instance(tc, self, *args)

Getting its backends from:

xpra/xpra/client/mixins/windows.py

Lines 634 to 638 in 08ce222

	def get_system_tray_classes(self) -> list[type]:
	# subclasses may add their toolkit specific variants, if any
	# by overriding this method
	# use the native ones first:
	return get_native_system_tray_classes()

Again, with the GTK client adding Gtk.StatusIcon as before:
https://github.com/Xpra-org/xpra/blob/08ce2221bf560530e42fc70fe1a6a11f6e53c262/xpra/client/gtk3/client_base.py#L822-L820

It used to be more complicated. (Unity misbehaving, Ubuntu and Debian breaking random things)
And I'm still not happy with this ridiculous dance we have to go through:

xpra/xpra/platform/posix/appindicator_tray.py

Lines 27 to 37 in 08ce222

	try:
	AppIndicator3 = gi_import("AyatanaAppIndicator3", "0.1")
	log("loaded `AyatanaAppIndicator3`")
	except (ImportError, ValueError):
	log("failed to load `AyatanaAppIndicator3`", exc_info=True)
	try:
	AppIndicator3 = gi_import("AppIndicator3", "0.1") # @UndefinedVariable
	log("loaded `AppIndicator3`")
	except ValueError as ve:
	log("failed to load `AppIndicator3`", exc_info=True)
	raise ImportError(f"failed to load `AppIndicator3`: {ve}") from None

So, I guess we should at least add an environment variable to allow users to choose the backend more easily.
And perhaps the window manager detection could be improved using an allow / deny list for each.
xpra wminfo does give us data we can use for the decision making.

[totaam]

With 7573ac0, now you can do:

XPRA_PREFER_STATUSICON=0 xpra attach ...

[sbradnick]

Works great! :)

Here's the output from that command, if it's of any use.

$ xpra wminfo
root=1362
WM_S0=3145730
_NET_SUPPORTING_WM_CHECK=3145741
wmname=i3
display=:0

[totaam]

Second thought, wminfo requires shelling out to be safe.
How about, env | grep XDG ?

[sbradnick]

Here's the output from the client, which is now making use of using eww's systray mechanism 👍

$ env | grep XDG
XDG_SESSION_PATH=/org/freedesktop/DisplayManager/Session0
XDG_SESSION_CLASS=user
XDG_VTNR=7
XDG_SESSION_TYPE=x11
XDG_SEAT=seat0
XDG_RUNTIME_DIR=/run/user/1000
XDG_SESSION_ID=3
XDG_SEAT_PATH=/org/freedesktop/DisplayManager/Seat0
XDG_CURRENT_DESKTOP=i3
XDG_GREETER_DATA_DIR=/var/lib/lightdm-data/scott
XDG_SESSION_DESKTOP=i3

And output from an xpra connection's shell:

$ env | grep XDG
XDG_CURRENT_DESKTOP=Xpra
XDG_RUNTIME_DIR=/run/user/1000
XDG_CONFIG_DIRS=/etc/xdg:/usr/local/etc/xdg:/usr/etc/xdg
XDG_SESSION_TYPE=x11

[totaam]

FWIW, I've changed the default in v6: 0ffeab6
It seemed safer than an always incomplete list of window managers.
It's a shame because Gtk.StatusIcon is much more usable for tray forwarding that any of the "newer" (supposedly "better") alternatives.

[sbradnick]

As of using e2d97e3 I can omit env XPRA_PREFER_STATUSICON=0 now when I run xpra attach and I still get the xpra tray icon so I can interact with the remote session 👍