Description

In Firefox 147 and newer versions, the address bar takes a fixed width and not the full width of the window:

Steps to Reproduce

1. Make sure you are using Firefox 147+.
2. Open out-of-scope site like preferences.
3. See that the address bar has incorrect width.

Additional Information

Since Firefox 147, likely because of changes in BZ-1986130/PHAB-D270553, making the URL bar read-only by temporarily hiding toolbar when constructing the URL bar (source) doesn't work anymore.

The URL bar still becomes read-only, but has a smaller fixed width, like it happened in BZ-1928550. This probably happens because the listeners for breakout and allowBreakout were still set during init, so some attributes like breakout=true are still set, probably because thecode ran after it had been initialized.

If I instead manually set window.gURLBar = false from the browser toolbox console, the URL bar becomes read-only, but it can still be selected and displays a popup with site suggestions.

I currently don't know how to fix this issue.

Environment

• Operating system: Windows 11
• System architecture: 64-bit
• Installation method: source
• PWAsForFirefox extension version: 2.17.2
• PWAsForFirefox native version: 2.17.2
• PWAsForFirefox runtime version: 148.0a1 (2025-12-27)
• Firefox version: 148.0a1 (2025-12-27)