2006515 - initial loading of fireflox in win11 with title bar doesn't call title bar

Status: RESOLVED DUPLICATE of bug 2002986

(Core :: Widget: Win32, defect)

Description

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Attachment: Screenshot 2025-12-16 185008.jpg

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:146.0) Gecko/20100101 Firefox/146.0

Steps to reproduce:

Customized interface with only one setting - Title Bar in lower left corner is checked.

This uses the OS borders and title bar instead of the standard firefox titlebar.

In Windows 11, launch firefox: there is no title bar at all and window is not resizable or movable because nothing to grab onto.

Opening a new windows behaves properly, just the first launch experiences the issue.

Hamburger menu -> More Tools -> Customize toolbar -> click Title Bar in the lower left -> Done

Close firefox and relaunch (from pinned taskbar instance) no borders or title bar appear.

Actual results:

Window appears and can be interacted with inside the borders and on the menu bar but not moved or resized or maximized or minimized, and double clicking the menu bar does nothing. right clicking on menu bar brings up a small menu bar setting: Turn on Vertical tabs, [] Menu Bar, Bookmarks, and Customize Toolbar.

Expected results:

OS title bar should appear and allow for grabbing and moving and resizing using the OS borders and title bar.

Comment 1

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Top right window in the image is the initial launch, which is missing the title bar and borders

lower left window in the image is a new windows created by using File -> New Window. this one has the title bar and is movable and resizable, and double clicking the title bar maximizes and minimized. Double clicking the menu bar on the new window does not maximize or minimize.

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::Widget: Win32' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 3

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Edition Windows 11 Pro
Version 25H2
Installed on ‎2/‎2/‎2025
OS build 26200.7462
Experience Windows Feature Experience Pack 1000.26100.275.0