Affected versions:

ALL

Affected platforms:

ALL

Prerequisites:

Access FF and enter in about:config.
Type devtools.responsive.metaViewport.enabled and set the value to "true".

Steps:

1. Open FF and access any website.
2. Hit Ctrl + Shift + M in order to start Responsive Design Mode.
3. Press Home page button (left side of the address bar).

Actual result:

The address bar is focused and the user is not redirected to the firefox home page.

Expected result:

The user should be redirected to the firefox home page.

Note: The issue is reproducible with or without touch simulation enabled.

Thanks for filing this issue!

The error I get in the console while reproducing this is:

Security Error: Content at moz-nullprincipal:{970469d9-d69a-46d9-a36a-ddd0ada9e276} may not load or link to about:home.

So I believe this bug is due to the swap/tunnel code. We're currently working toward building a new version of RDM where it does not rely on this mechanism. When that project is finished, this issue should also go away. I'll add this issue as another blocker to the rdm-tunnel meta bug.