1718757 - Firefox is not automatically set as the default web browser if the browser is opened in Windows 8 compatibility mode

Status: RESOLVED WONTFIX

(Firefox :: Shell Integration, defect)

Description

[Marius Coman [:mcoman], Ecosystem QA]

Attachment: rec of the issue.gif

[Affected versions]:

• Firefox Nightly 91.0a1 - Build ID: 20210630093648

[Affected Platforms]:

• Windows 10 x64

[Prerequisites]:

• Have the browser set to be opened in Windows 8 compatibility mode.
• Firefox is NOT set as the default web browser.

[Steps to reproduce]:

1. Open the browser with the profile from prerequisites.
2. Navigate to the "about:preferences" page and click the "Make Default..." button.
3. Observe the behavior.

[Expected result]:

• Firefox is automatically set as the default web browser.

[Actual result]:

• Firefox is not set as the default web browser and the "Default apps" OS window is opened.

[Notes]:

• This issue is reproducible regardless of the method used for setting the browser as the default one.
• Attached a screen recording of the issue.

Comment 1

[Masatoshi Kimura [:emk]]

That's because AppConstants.isPlatformAndVersionAtLeast is tricked by the compatibility mode. In C++ code, IsWin10OrLater should be used which is immune to the compatibility shim. Is IsWin10OrLater exposed to JS?

Comment 2

[Adam Gashlin (he/him) [:agashlin] (ex-moco)]

(In reply to Masatoshi Kimura [:emk] from comment #1)

That's because AppConstants.isPlatformAndVersionAtLeast is tricked by the compatibility mode. In C++ code, IsWin10OrLater should be used which is immune to the compatibility shim. Is IsWin10OrLater exposed to JS?

I don't think IsWin10OrLater is exposed to JS. In my opinion we don't need to work around compatibility mode here: it should be rare, the fallback still behaves as expected, and I don't want to get into the business of second-guessing compatibility mode. This is slightly more WONTFIX than INVALID, though, if it's more important than I know please reopen.