User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.5005.63 Safari/537.36 Edg/102.0.1245.33

Steps to reproduce:

After 102 beta 1 RSS feed messages with URL link started to open the same web page twice in browser when the link is clicked in the message pane (3 panes vertical view).
Same problem with 102 beta 2 and 102 beta 3.
Worked fine with 101 beta 4 and all Thunderbird versions before that.

Actual results:

URL opens in web browser twice

Expected results:

URL should open just one browser page/tab.

It only opens once for me.

example link

That's odd. And you click the link in the preview window? Example picture from Youtube RSS feed attached.
If instead of using the preview window I open the RSS message and then click the URL link in that window, then my browser opens just one tab.
If I downgrade back to 101.b4 then also the preview window url works again correctly. So something was changed.

Yes I clicked that (I only tried Daily though).

I changed pane layout to wide view and then I got 4 browser tabs opening. I then changed back to vertical view and now I got 5 browser tabs when I click RSS' url. I made a backup of Thunderbird's user profile before this and when I copied it back, I'm now back in 2 browser tabs opening "mode". Very weird. Please try to change view modes in your system and see if this starts to happen.

I changed to classic view and restarted Thunderbird and now it opens just one browser tab. But when I go back to vertical 3 pane view, it opens again two browser tabs...

Oh, I see that now

Otherweise RSS feed URL links open twice after switching view mode (classic/wide)

Pushed by mkmelin@iki.fi:
https://hg.mozilla.org/comm-central/rev/e1db7dc68c52
Only run connectedCallback once for url-header-row. r=aleca

Comment on attachment 9280258 [details]
Bug 1773013 - Only run connectedCallback once for url-header-row. r=aleca

[Approval Request Comment]
Regression caused by (bug #): bug 1764652
User impact if declined: links from rss url header line open more than once after switching modes
Testing completed (on c-c, etc.): c-c
Risk to taking this patch (and alternatives if risky): safe

Comment on attachment 9280258 [details]
Bug 1773013 - Only run connectedCallback once for url-header-row. r=aleca

[Triage Comment]
Approved for beta

Thunderbird 102.0beta6:
https://hg.mozilla.org/releases/comm-beta/rev/2d23482dfad7