QSystemTrayIcon does not render SVGs on arch

Hi,

when instanciating QSystemTrayIcon with a QIcon initialized from a SVG file, it does not render, but it still is clickable and shows a menu. You can find a screenshot at this related issue.

Weirdly, the issue occurs only inside plasma, but not inside e.g. awesome-wm on the same system. Furthermore, the issue occurs only with the arch's system package of PyQt5, but not with the one installed using `pip install` into a virtualenv (same version of python/pyqt otherwise).

Example python code:

from PyQt5.QtGui import QIcon
from PyQt5.QtWidgets import QApplication, QSystemTrayIcon
import signal
import sys

app = QApplication(sys.argv)
signal.signal(signal.SIGINT, signal.SIG_DFL)
icon = QIcon('tray.svg')
tray = QSystemTrayIcon(icon)
tray.show()
app.exec_()

Example tray.svg:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg width="128" height="128" viewBox="0 0 100 100" version="1.1" xmlns="http://www.w3.org/2000/svg">
<path stroke="#000000" fill="none" stroke-width="12" d="M 20,35 L 40,75 L 80,25"/>
</svg>

A workaround is to convert the icon to QPixmap and back:

icon = QIcon(QIcon('tray.svg').pixmap(32))

Furthermore, if executing the program from a remote login session (SSH, setting DISPLAY=:0 to the running session) the icon shows correctly inside plasma even without the workaround, and with using arch's system python/pyqt. However, not anymore after setting the environment variable KDE_FULL_SESSION to any value.

On the other hand, when running inside plasma, the presence of KDE_FULL_SESSION and other KDE related variables does not prevent the issue, and setting them does not cause the behaviour when running the PyPI version.

I originally added this info to QTBUG-53550 and was asked by jirauser22264 to report this here.

The archlinux packaging scripts are easy to obtain from archlinux.org, e.g. here the one for python-pyqt5 and then looking at Source Files -> PKGBUILD. The site also links all the build and runtime dependencies.