Preferred Applications-does it work???

Has anybody had any success with this.
If you have enabled advanced menu/ settings/Preferred applications.
I have added Thunderbird, listed in the AM, changed the email client in PA, it was automatically listed , even entered it in the other option in PA, removed the account off One Mail too, rebooted many times but no..............!!!! it doesnt work.
Checked the help section of XFce too

Would like that the icon and the received email in the taskbar will default to T.

Will if all else fails have a go again at editing the xfce group file covered in previous topics. However have had issues with this with it all defaulting back to the factory setting so not confident.
Wonder if the Xfce plugin called Home or something like this- that is listed in the software installed ,has something to do with this last issue- is this somekind of back up feature that "helpfully" resets it in case of people meddling??.
Oh well fun problem solving but must get on with life!!!

 

Yes I have Opera as my default browser and Thunderbird as my mail client, if I open an email with a URL link I just click and Opera will open with the desired link page.