The feed preview is not populated correctly when switching between tabs.

1.) Load https://www.seamonkey-project.org/ which shows the preview icon.
2.) Go to Download and Releases https://www.seamonkey-project.org/releases/ which does not show it because this page does not have rss.
3.) Now open a second tab and switch to it to it. Url does not matter.
4.) Switch back to the SeaMonkey project page. You will now see the rss icon.

There are variations where the feeds will double if you open the popup menu. Also you might see a log error when you use some more complex navigation between tabs and try to open the popup feeds menu:

Timestamp: 9/21/2020, 10:01:04 PM
Error: TypeError: can't access dead object
Source File: chrome://navigator/content/nsBrowserStatusHandler.js
Line: 148

Seems to be bad interaction between tabbrowser.xml and suite/browser/nsBrowserStatusHandler.js

SeaMonkey 2.44 was the last version working right. Probably regressed by Bug 1272401 or the underlying Gecko changes.

[Approval Request Comment]
Regression caused by (bug #): --
User impact if declined: Just some prerequisite cleanups I did when checking the code for errors.
Testing completed (on m-c, etc.): 2.53.11b1pre
Risk to taking this patch (and alternatives if risky): trivial
String changes made by this patch: --

mFeeds was never initialized again after creating the listener. onLocationChange in the status browser handler clears it but not always fired too and then repoulates with the bad cache too resulting in duplicate or defunct items in some cases.

See removal in:
https://hg.mozilla.org/comm-central/rev/dd8fa7b8bd65#l1.254

[Approval Request Comment]
Regression caused by (bug #): Bug 1272401
User impact if declined: defunct feeds icon in the url bar and errors in console.
Testing completed (on m-c, etc.): 2.533.11b1pre
Risk to taking this patch (and alternatives if risky): low risk. Worst case is either a missing feeds icon or bad (old) behaviour if I picked the wrong location.
String changes made by this patch: --

Comment on attachment 9256824 [details] [diff] [review]
1716221-tabbrowsererci-25311.patch

[Triage Comment]
LGTM r/a=me

Comment on attachment 9256825 [details] [diff] [review]
1716221-fixfeeds-25311.patch

Just wondering if it should go into onLocationChange around https://hg.mozilla.org/comm-central/file/tip/suite/browser/tabbrowser.xml#l682
if (!isSameDocument)
this.mFeeds = [];

Comment on attachment 9256825 [details] [diff] [review]
1716221-fixfeeds-25311.patch

[Triage Comment]
r/a=me after reading the bug comments better :)

Pushed by frgrahl@gmx.net:
https://hg.mozilla.org/comm-central/rev/0524c4d2e262
Remove unneded Ci definitions in tabbrowser. r=IanN
https://hg.mozilla.org/comm-central/rev/994b05cff95d
Clear feeds in tabbrowser for a toplevel network state change. r=IanN

https://gitlab.com/seamonkey-project/seamonkey-2.53-comm/-/commit/be33069caec25316a9b7b505482260c0cd0308a1
Remove unneded Ci definitions in tabbrowser. r=IanN a=IanN
https://gitlab.com/seamonkey-project/seamonkey-2.53-comm/-/commit/c1eae55f8bffc117dd6bb8ad6cc94688495ca41c
Clear feeds in tabbrowser for a toplevel network state change. r=IanN a=IanN