Windows 11 taskbar not disappearing in fullscreen when there's PIP window.

Do you remember if this used to work differently before?

(For context: support.mozilla.org/questions/1589313 — the same report, also unsure if recent change exactly.)

I recently installed firefox few weeks ago, I noticed this issue just recently (1 week or so).

I've encountered this issue after the 152.0 major update. But I haven't used firefox with their PIP in fullscreen before 152.0 update.

So I don't know which update caused this.

I've tested with the nightly versions as stated in this article: https://support.mozilla.org/en-US/questions/1589313

Tested versions: - https://ftp.mozilla.org/pub/firefox/nightly/2026/04/2026-04-19-20-35-36-mozilla-central/firefox-151.0a1.en-US.win64.installer.exe - https://ftp.mozilla.org/pub/firefox/nightly/2026/05/2026-05-28-09-04-16-mozilla-central/firefox-153.0a1.en-US.win64.installer.exe

Both versions were able to hide the windows taskbar as intended.

Also tested with normal firefox with a new profile, the issue still persists.

Hmmh that is interesting since these versions are on both sides of the current release so normally it would be expected to have one of them "good" and the other "bad", so this can be something else potentially. To double check, if you run the latest Nightly available on nightly.mozilla.org is that one also "good" or "bad"?