2064638 - On MacOS, when firefox is in a Space (so fullscreen), vertical tabs do not show when going to edge of screen

Status: NEW

(Firefox :: Sidebar, defect, P1)

Description

[Jordan]

Steps to reproduce:

OS: MacOS Tahoe 26.6.1
FIrefox 154.0

Put Firefox into a Space (i.e. fullscreen)
Toolbars auto hide themselves, top toolbar set to auto-hide
Vertical Tabs now hide themselves too
Tried going to left edge of screen to show vertical tabs

Actual results:

Vertical tabs do not show themselves.
Going to top edge for the top toolbar shows everything, but moving cursor to hover over vertical tabs causes it to close again if not quick enough/directly over a tab and showing tooltip

Note: I believe it comes from a new fix in the latest build of Firefox.
Quote - Fixed the Vertical Tabs sidebar staying visible in full screen mode. It now hides along with the toolbars and reappears when the cursor moves to the edge of the screen.

Expected results:

Vertical tabs should show when hovering left edge of screen and stay there until done hovering.

Comment 1

[BugBot [:suhaib / :marco]]

The Bugbug bot thinks this bug should belong to the 'Firefox::Sidebar' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Sylvestre Ledru [:Sylvestre]]

maybe i regressed it

Comment 3

[BugBot [:suhaib / :marco]]

:kcochrane, since you are the author of the regressor, bug 2047653, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 5

[Stephen Thompson [:sthompson]]

Planning to have a fix and uplift to 155 dot release

Comment 6

[Sylvestre Ledru [:Sylvestre]]

Attachment: WIP: Bug 2064638 - Let the sidebar be reached from the screen edge in fullscreen r?#sidebar-reviewers,#firefox-desktop-reviewers

Bug 1927457 made the sidebar launcher hide along with the autohidden nav
toolbox in fullscreen. Only the top of the screen brings the chrome back
though, so vertical tabs ended up out of reach: moving to the edge where they
sit does nothing.

Watch for the pointer reaching the launcher's edge of the screen and bring the
chrome back there too, so reaching for the tabs works like reaching for the
toolbar. This goes through MousePosTracker rather than a hover target at the
edge: an element there would also catch a pointer that merely happens to rest
at the edge when the chrome collapses and reveal it again the moment it
appeared, and it would sit over the content while it did. Nothing is watched
when there is no launcher to reach for, or in DOM fullscreen, which leaves the
nav toolbox collapsed on its way out.

Reaching the tabs also has to keep them. MousePosTracker hides the chrome again
once the pointer enters the content area, and showNavToolbox seeded that rect
from the collapsed layout, where the launcher takes no space - so the area the
launcher was about to reveal into counted as content, and touching a tab could
send everything away again. Capture the rect while the chrome is still
expanded instead, since showing it restores exactly that layout.

The chrome then has to be able to go away again. Revealed with the pointer
already in the content area, addListener's synchronous enter finds us still
collapsed and bails, but leaves the pointer recorded as inside. The tracker
only reports transitions, so no later move could hide the chrome and it stayed
up for good - reproducible in macOS native fullscreen, where the OS menubar
sliding down reveals the chrome without the pointer ever being over the
toggler. Forget that enter so the next move is one.

That menubar also sends a reveal update for every frame of its slide down.
Taking each one as a reveal put the chrome straight back after the pointer
returning to the content sent it away, which reads as the content jumping, so
only the start of the reveal counts. Its shift now goes through one place as
well, because a collapsed toolbar that keeps it hangs that far over the
content until the menubar goes back up.

None of this runs on macOS as shipped: browser.fullscreen.autohide has been
false there since bug 740148, so fullscreen keeps the toolbars - and, since
bug 1927457, the sidebar - in place, unlike every other platform. Turn it on
for platform parity, which is what bug 1702563 asks for.

That also makes three tests worth running on macOS. Two opted out only because
the toolbars stayed put there: browser_fullscreen_enterInUrlbar.js says as
much in its own header comment, and browser_fullscreen_autohide_toolbox_height.js
points at bug 1702563. browser_f11_fullscreen_sidebar.js was skipped for the
same reason but turns the pref on itself, so it gives this fix coverage in
native fullscreen, the mode the bug was reported in.

Comment 7

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 1927457