Is there a way to NEVER hide icons in the System Tray?

Opening the System Tray settings and selecting "Always Visible" in all icons is not enough, as new icons will be hidden anyway until you open the settings again and set "Always Visible" for the new icon.

I've not seen this option in the settings window, but maybe someone can point me to some setting to be changed in a config file...

Thanks in advance.

As far as I know, this isn't possible. You may wish to file a feature request at bugs.kde.org.

I don't think this is likely to happen, developers are resistant to putting another config option unless there is a really good reason, and I doubt this would qualify since you shouldn't be adding system tray entries all that often.