Ubuntu 17.10 small tray icons

You can't remove gnome-shell-extension-appindicator, ubuntu-desktop depends on it. Solution that works for me (but You do it on your own risks):

sudo apt-get remove gnome-shell-extension-appindicator
apt-get download ubuntu-desktop
sudo dpkg --install --ignore-depends=gnome-shell-extension-appindicator ubuntu-desktop_1.404_amd64.deb

For ignoring broken packages in Ubuntu (from this source), run:

sudo gedit /var/lib/dpkg/status

This should open the file status (which can be pretty long), you now have to find the package name ubuntu-desktop. Now delete the dependencies gnome-shell-extension-appindicator from the Depends line, save the file (Ctrl+S) and close.

Now install TopIcons Plus and KStatusNotifierItem/AppIndicator Support.

I have the same problem after upgrading from Ubuntu Gnome 17.04. I tried a lot of fixes, but none of them helped me. I decided to reinstall Ubuntu. After a fresh install, the issue still persists, but there is a kind of workaround that is working for me. As described here: In terminal execute export XDG_CURRENT_DESKTOP=Unity then run the app ./Telegram & exit. The result is a litte bit bigger icon in the tray and a badge indicator on the icon in the dock.

You have to edit /usr/share/applications/telegramdesktop.desktop which is telegram launcher. Change line

Exec=telegram-desktop -- %u

to

Exec=env XDG_CURRENT_DESKTOP=Unity telegram-desktop -- %u

You can do the same workaround for Slack too.

You may first install TopIcons Plus from extensions.gnome.org or its GitHub page.

But the default Ubuntu appindicators will not let TopIcons Plus work properly. So you will have to deactivate/remove it first.

You may deactivate Ubuntu appindicators from the Extensions section of (GNOME) Tweaks (suggested by Charles Green). To install Tweaks run

sudo apt install gnome-tweak-tool

_{Alternatively if you are absolutely sure that you want to remove Ubuntu appindicators, then run (not at all recommended, it will remove ubuntu-desktop metapackage)}

sudo apt-get remove gnome-shell-extension-appindicator 

_{or remove the [email protected] directory from /usr/share/gnome-shell/extensions.}

Now TopIcons Plus should work as expected. You may change its settings using the indispensable GNOME Tweak Tool (aka Tweaks). If it is not installed, you can install it by

sudo apt install gnome-tweak-tool

Then launch GNOME Tweak Tool and change the settings of TopIcons Plus (for example icon size, spacing etc.) from the Extensions section.