hover info won't show in KDE (kubuntu 19.10)

[mxa]

The hover info as described in the README is not showing in Kubuntu 19.10.

[mxa]

This is the release version via the python package manager, but I think it's also the case with the git version, let me know if you need me to check this.

[SpotlightKid]

I experience the same issue on Manjaro with Xfce4/xfwm4/xfce4-panel. But weirdly enough, it works on one of my computers, but not on the other. Both run the same up-to-date Manjaro distribution and use the same desktop. The laptop, where it doesn't work was installed much more recently and may have slightly different themes installed and different desktop / theme settings enabled.

I tried debugging this by inserting a debug logging call into jackselect.jackselect:JackSelectApp.tooltip_query():

    def tooltip_query(self, widget, x, y, keyboard_mode, tooltip):
        """Set tooltip for the systray icon."""
        log.debug("Tooltip query: widget=%s, x=%d, y=%d, mode=%s, tooltip=%r",
                  widget, x, y, keyboard_mode, tooltip)
        ...

But even on the desktop where the tooltips are not shown, the callback is called whenever mouse events occur over the app's icon in the systray, e.g:

[...]
[jack-select] DEBUG: Tooltip query: widget=<Gtk.StatusIcon object at 0x7f6dfb613100 (GtkStatusIcon at 0x5588bc9cf880)>, x=14, y=11, mode=False, tooltip=<Gtk.Tooltip object at 0x7f6dfb5a0900 (GtkTooltip at 0x5588bca811b0)>
[jack-select] DEBUG: Tooltip query: widget=<Gtk.StatusIcon object at 0x7f6dfb613100 (GtkStatusIcon at 0x5588bc9cf880)>, x=12, y=10, mode=False, tooltip=<Gtk.Tooltip object at 0x7f6dfb5a0900 (GtkTooltip at 0x5588bca811b0)>
[jack-select] DEBUG: Tooltip query: widget=<Gtk.StatusIcon object at 0x7f6dfb613100 (GtkStatusIcon at 0x5588bc9cf880)>, x=10, y=7, mode=False, tooltip=<Gtk.Tooltip object at 0x7f6dfb5a0900 (GtkTooltip at 0x5588bca811b0)>
[jack-select] DEBUG: Tooltip query: widget=<Gtk.StatusIcon object at 0x7f6dfb613100 (GtkStatusIcon at 0x5588bc9cf880)>, x=6, y=1, mode=False, tooltip=<Gtk.Tooltip object at 0x7f6dfb5a0900 (GtkTooltip at 0x5588bca811b0)>
[...]

The same logging messages are generated on the computer where the tooltip is shown.

Also, none of the other systray apps I have running show any tooltips as well. So this seems to be a general problem with systray icon tooltips, rather than something specific to jack-select.