Solved: Missing ktorrent icon on Linux Mint / Cinnamon

Running ktorrent on Linux Mint 19 (Tara), the famous downwards-arrow icon was invisible on the system tray. Which made it appear like the program had quit when it was actually minimized. Clicking the empty box made ktorrent re-appear.

Solution: Invoke the Qt5 configuration tool

$ qt5ct

and under the Appearance tab set “Style” to gtk2 (I believe it was “Fusion” before). It’s not just prettier generally, but after restarting ktorrent, the icon is there.

Actually, it’s probably not about the style, but the fact that qt5ct was run. Because before making the change, the ktorrent printed out the following when launched from the command line:

Mon Dec 24 09:52:55 2018: Qt Warning: QSystemTrayIcon::setVisible: No Icon set
Warning: QSystemTrayIcon::setVisible: No Icon set
Mon Dec 24 09:52:55 2018: Starting minimized
Mon Dec 24 09:52:55 2018: Started update timer
Mon Dec 24 09:52:55 2018: Qt Warning: inotify_add_watch("/home/eli/.config/qt5ct") failed: "No such file or directory"
Warning: inotify_add_watch("/home/eli/.config/qt5ct") failed: "No such file or directory"

The “No Icon set” warning is misleading, because it continued to appear. This is after the fix, with the icon properly in place in the tray:

Mon Dec 24 10:16:17 2018: Qt Warning: QSystemTrayIcon::setVisible: No Icon set
Warning: QSystemTrayIcon::setVisible: No Icon set

Anyhow, problem fixed. For me, that is.

And why ktorrent? Because its last reported vulnerability was in 2009, compared with “Transmission” which had a nasty issue in January 2018. Actually, the exploit in Transmission is interesting by itself, with a clear lesson: If you set up a webserver on the local host for any purpose, assume anyone can access it. Setting it to respond to 127.0.0.1 only doesn’t help.