[PySide6] QSystemTrayIcon bug when using Class

Salamafet

Hi,

I am trying to create a multiplatform system tray application.

My code is tested on macOS 14.2 with Python 3.11.4 and PySide 6.6.1 .

Here is my code :

import sys
from PySide6 import QtCore, QtWidgets, QtGui

class Tray(QtWidgets.QSystemTrayIcon):
    def __init__(self):
        super().__init__()

        self.setIcon(QtGui.QIcon("logo.icns"))
        self.setVisible(True)

        menu = QtWidgets.QMenu()

        action = QtGui.QAction("Hello World !")
        menu.addAction(action)

        quit = QtGui.QAction("Quit")
        quit.triggered.connect(app.quit)
        menu.addAction(quit)

        self.setContextMenu(menu)

if __name__ == "__main__":
    app = QtWidgets.QApplication([])
    app.setQuitOnLastWindowClosed(False)
    app.setWindowIcon(QtGui.QIcon("logo.icns"))

    tray = Tray()

    sys.exit(app.exec())

In this example, the icon in the system tray appears but nothing append when I click on it.

If I omit the class and put the code directly in my __name__ block, I works great.

import sys
from PySide6 import QtCore, QtWidgets, QtGui


if __name__ == "__main__":
    app = QtWidgets.QApplication([])
    app.setQuitOnLastWindowClosed(False)
    app.setWindowIcon(QtGui.QIcon("logo.icns"))

    tray = QtWidgets.QSystemTrayIcon()

    tray.setIcon(QtGui.QIcon("logo.icns"))
    tray.setVisible(True)

    menu = QtWidgets.QMenu()

    action = QtGui.QAction("Hello World !")
    menu.addAction(action)

    quit = QtGui.QAction("Quit")
    quit.triggered.connect(app.quit)
    menu.addAction(quit)

    tray.setContextMenu(menu)

    sys.exit(app.exec())

How can I use QSystemTrayIcon with a class to keep a code clean and structured ?

friedemannkleint

Try keeping a reference to the menu in the class:

self._menu = QMenu()

...

JonB

@friedemannkleint
You are doubtless correct (your posts usually are!) for some Python reference counting reason this is correct. (It is certainly worth the OP trying.) But why doesn't the existing line self.setContextMenu(menu) keep the required reference count to menu above 0 here anyway?

Salamafet

@friedemannkleint
Same problem with self.menu.

JonB

@Salamafet
Hmm, then as I suggested it's not that.

In this example, the icon in the system tray appears but nothing append when I click on it.

You see the tray icon? When you click on it you do not get to see any Quit action on it, or you see the action but nothing happens when you click on it?

Like you I am not clear what difference the class is making. If you are saying the item appears but the quit action is not triggered try

quit.triggered.connect(lambda: print("action triggered"))

If you want to get further any QObject-derived object (most of the ones you create) can have object.destroyed.connect(lambda: print("object destroyed")) attached. Would tell you if anything unexpected is getting destroyed after you created it.

Salamafet

@JonB

I see the tray icon, but there is no dropdown menu when I click on it.
This is like there is no action in the menu.

The behavior is the same as if I used this code :

import sys
from PySide6 import QtCore, QtWidgets, QtGui

if __name__ == "__main__":
    app = QtWidgets.QApplication([])
    app.setQuitOnLastWindowClosed(False)
    app.setWindowIcon(QtGui.QIcon("logo.icns"))

    tray = QtWidgets.QSystemTrayIcon()

    tray.setIcon(QtGui.QIcon("logo.icns"))
    tray.setVisible(True)

    sys.exit(app.exec())

JonB

@Salamafet
Yet you say if you move the action/addAction() code out of the class and into the __main__ area you do see it?

Although I absolutely do not see why this should be necessary, try

self._menu = QtWidgets.QMenu()
self._action = QtGui.QAction("Hello World !")    # this line too
self._menu.addAction(self._action)

when inside the class?

Salamafet

@JonB

Yet you say if you move the action/addAction() code out of the class and into the main area you do see it?

Yes, in this case it's works.

By adding self on each variable in class, it's works. I don't understand why, but it works.

Thanks a lot

JonB

@Salamafet said in [PySide6] QSystemTrayIcon bug when using Class:

I don't understand why, but it works.

Well the reason is that when Python detects nothing is refencing any Python object it destroys it --- that's the object collection the language gices you unlike plain C++.

The mystery is that one would have thought that self.setContextMenu(menu) would itself increment the reference count on menu and its action added to that. I don't know why it does not. I don't know whether menu = QtWidgets.QMenu(self) inside Tray() would have improved the situation. You might like to add that anyway, and then maybe see if the other 2 changes are no longer required.

Ah, see (the C++ explanation for) [void]QSystemTrayIcon::setContextMenu(QMenu *menu) (or PySide6 PySide6.QtWidgets.QSystemTrayIcon.setContextMenu(menu)):

Note: The system tray icon does not take ownership of the menu. You must ensure that it is deleted at the appropriate time by, for example, creating the menu with a suitable parent object.

This explains everything. Whenever it says "something does not take ownership of this QObject" that will mean the Python code will not increment a reference count. setContextMenu() leaves you in charge of the menu, which e.g. you might be using elsewhere. Consequently any QObjects documented like that will require (typically) a Python self._variable = TheObject() to keep it "alive" for the duration of the class instance, not just a local variable. Or, by the looks of it even better, pass self to the top-level object's constructor (your QMenu()) so it is fully owned by the instance.