I don't travel much with my laptop so my home network connection remains more or less static. Nonetheless I have noticed for some time that the nm-applet does not appear in my system tray. Manually launching nm-applet succeeds and the icon appears in the tray.
Eventually I traced the problem to the desktop file:
NotShowIn=KDE;GNOME;
Removing the 'KDE' directive allows nm-applet to launch in TDE. The problem with that is KDE has its own NetworkManager front-end and nm-applet is not needed. So the KDE directive is needed.
The mystery is why is TDE interpreting 'KDE' to mean 'TDE'?
This seems like a bug but perhaps there is an explanation I am not seeing.
I found a list discussion from about 10 years ago that seemed similar. In that discussion nm-applet was launching but the icon was not displaying correctly. In my case nm-applet is not launching unless I remove the 'KDE' directive from the desktop file.
I know about tdenetworkmanager. Not important to this discussion. I first want to understand why TDE is incorrectly interpreting 'KDE' as 'TDE' or acting as though TDE is KDE.
Thanks.