User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:72.0) Gecko/20100101 Firefox/72.0

Steps to reproduce:

1. Download, unzip, and install the test extension.
2. Click on the sidebarAction.
3. Open the extension debug console.

Actual results:

getViews({}) returns an array containing the background page, the browserAction window, the tabbed extension page window, and the sidebar window.

getViews({windowId}) returns an array containing the browserAction window, and the tabbed extension page window. IT DOES NOT CONTAIN THE SIDEBAR WINDOW.

Expected results:

getViews({windowId}) should return an array containing the the sidebar window.

Hello,
I have managed to reproduce the issue on the latest Nightly (74.0a1/20200203085242), Beta (73.0b11/20200128001646) and Release (72.0.2/20200117190643) under Windows 10 Pro 64-bit and macOS Catalina 10.15.
The getViews({windowId}) does not contain the sidebar window.

Fixing this in bug 1708243 part 1.

https://hg.mozilla.org/mozilla-central/rev/2f684ad43258

Needs an entry for the release notes of 93 at https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/93#changes_for_add-on_developers
And a notice that extension content in sidebars were not returned when windowId is set prior to Firefox 93.

A browser-compat-table entry is likely not needed since sidebar is only supported by Firefox (and Opera?).

Will this fix be populated to older versions? Should a note be added to MDN (https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/extension/getViews) saying that it won't work as expected in older Firefox versions?

(In reply to Danny Lin from comment #4)

Will this fix be populated to older versions?

The fix landed in 93 and won't be backported to older Firefox versions.

Should a note be added to MDN (https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/extension/getViews) saying that it won't work as expected in older Firefox versions?

Yes. This is what I meant by

And a notice that extension content in sidebars were not returned when windowId is set prior to Firefox 93.

Documentation changes are in Sidebars included in extension.getViews when windowId specified #8399 .

With regard to:

A browser-compat-table entry is likely not needed since sidebar is only supported by Firefox (and Opera?).

I note that the browser compatibility table includes a Firefox-specific note with regard to behavior in private windows, therefore, it would not seem inappropriate to include details of this too.

(In reply to Richard Bloor from comment #6)

Documentation changes are in Sidebars included in extension.getViews when windowId specified #8399 .

With regard to:

A browser-compat-table entry is likely not needed since sidebar is only supported by Firefox (and Opera?).

I note that the browser compatibility table includes a Firefox-specific note with regard to behavior in private windows, therefore, it would not seem inappropriate to include details of this too.

Ok, go ahead and add an entry for the windowId property and add this as a note.
And mark windowId in Firefox for Android as partial support: the property is recognized, but the filter doesn't work.