Icon would draw properly with Tg logo
N/A icon is shown
If I restart Telegram with "killall Telegram" and relaunch it, the icon is still N/A after relaunch.
Operating system:
Ubuntu 14.04.3 LTS
Version of Telegram Desktop:
0.9.42
Nothing relevant

Related to #1411?
I researched this issue. There is a couple of qt bugs about tray icons. Under mate, Qt 5.6.0 generates the issue reported above. I tried to build another Qt app with tray icon under Qt 5.0.2, the tray icon appears normally, without any issue.
There are several Qt releases without tray icon problems, see the Qt bugs database.
I created a Qt bug about this issue: https://bugreports.qt.io/browse/QTBUG-54345
I will try to rebuild Telegram Desktop with Qt 5.0.2, will tell whether I succeeded with build process and tray icon.
One can get Qt 5.0.2 at https://download.qt.io/archive/qt/5.0/5.0.2/
Does not build under Qt 5.0.2 =)) codegen_style fails to build due to " http://doc.qt.io/qt-5/qmap.html#QMap-1 This function was introduced in Qt 5.1. " and also due to other errors.
So I might try to find another Qt >= 5.1 which has sane tray icons for Mate
P.S. Tg page https://github.com/telegramdesktop/tdesktop also mentions Qt 5.3.2 as a supported version.
@egphilippov You can try Qt 5.3.2. Code branch mac32 is built against that Qt version for OS X 10.6 and 10.7 support.
A failure. Qt 5.3.2 builds another tray icon app so that the tray icon seems to be invisible at all under Mate.
Qt 5.5.1 behaves seemingly exactly like Qt 5.6.0 wrt tray icon / mate.
https://download.qt.io/archive/qt/5.5/5.5.0/qt-opensource-linux-x64-5.5.0-2.run behaves seemingly exactly like Qt 5.5.1 and 5.6.0.
Qt 5.1.1 behaves like Qt 5.3.2.
Under Qt 5.7.0 ( 15-Jun-2016 ), the icon's image displays properly and correctly (as expected), but the mouse signals are not delivered (trigger, double click, middle click do not generate the signal activated(QSystemTrayIcon::ActivationReason))
The following comment might be a bit relevant: "I have builded QT-5.5.0-alpha1(on Linux Mint 17.1 64-bit) and tested showing of icon in system tray with kadu (polish instant messenger, http://www.kadu.im). I've been starting many times kadu on Mate desktop environment and 100% working." from here https://bugreports.qt.io/browse/QTBUG-35658
I found a great solution:
dbus-launch ~/bin/TelegramDesktop/Telegram -- %u
It works completely OK under Mate. The icon displays Telegram logo and mouse clicks are handled as they should.
Thanks to http://askubuntu.com/questions/732967/dropbox-icon-is-not-working-xubuntu-14-04-lts-64 .
@hypnosis-i2p https://github.com/telegramdesktop/tdesktop/issues/1716#issuecomment-219225923 馃檲
I have a report that the dbus-launch solution also works in KDE on kubuntu 14.04 for Dropbox icon.
Most helpful comment
I found a great solution:
dbus-launch ~/bin/TelegramDesktop/Telegram -- %uIt works completely OK under Mate. The icon displays Telegram logo and mouse clicks are handled as they should.
Thanks to http://askubuntu.com/questions/732967/dropbox-icon-is-not-working-xubuntu-14-04-lts-64 .