Non-Interaction Faults (in numerical order)
Firefox Bug 306208
Links: Bug Report, Fix Comment, and Fix Attachment
Explanation: When Firefox was configured to display the tab strip without checking the number of tabs in the window (so that the tab strip would appear even with only one tab), it also ignored the check for toolbar visibility, so the tab strip would display even when the toolbar was hidden. The fix added the missing check in the optional code.
Summary: The fault was confined to an optional feature.
Firefox Bug 337871
Links: Bug Report, Fix Comment, Fix Attachment, and Separate Test Case
Explanation: Any changes to spell-checking ranges, even removing them, would cause Firefox to scroll their rectangle into view. Therefore, when inline spell-checking was enabled and the user moved focus from one textbox to another, Firefox would try to scroll the old one into view to remove its spell-checking range and then scroll to the new one to add a range—the screen would "jump." The fix added checks to the scrolling code so that it only applied to some range changes.
Summary: A fault in common code was exposed by an optional feature.
Firefox Bug 344189
Links: Bug Report, Fix Comments 1 and 2, and Fix Attachment
Firefox Bug 403040
Links: Bug Report, Fix Comment, and Fix Attachment
Explanation: If the setting for the amount of history to retain was missing, Firefox would default to zero (disabling history), rather than a more typical value. The fix changed the default value.
Summary: When unspecified, a feature would default to disabled whereas it was expected to be enabled.
Firefox Bug 403854
Links: Bug Report, Fix Comment, and Fix Attachment
Explanation: Before the fix common code referred to two UI elements without checking whether they were null. But UI customization could nullify their values; the fix added a nullness check.
Summary: A fault in common code was exposed by an optional feature.
Firefox Bug 413437
Links: Bug Report, Fix Comment, and Fix Attachment
Explanation: Before the fix UI code was not checking whether a preference was configured as locked, so the preference was effectively always unlocked. The fix added a guard.
Summary: Part of the configuration was not being read.
Firefox Bug 414836
Links: Bug Report, Fix Comment, and Fix Attachment
Explanation: After upgrading from a sufficiently old Firefox version to a version without the fix, some toolbar configurations would continue to appear in the settings dialog, but not actually apply. Only by changing the settings and then changing them back could the configuration be properly stored and apply everywhere. The fix changed the CSS id of the toolbar so that old preferences no longer applied to it---the customizations were consistently lost in the upgrade.
Summary: The configuration was not being read consistently.
Firefox Bug 423960
Links: Bug Report, Fix Comment, and Fix Attachment
Explanation: In a Firefox configuration disabled history manifests as a maximum history expiration time of zero. Normally Firefox checks that the maximum expiration time is at least the minimum expiration time and increases the maximum if necessary. Here, however, the maximum ought not to change, so the fix added a check for a zero expiration time.
Summary: A configuration option that should have made another irrelevant was instead ignored in favor of the other.
Firefox Bug 442970
Links: Bug Report, Fix Comment, and Fix Attachment
Explanation: When configured to show windows and tabs from last time, Firefox would do so, but also load the homepage in a tab. This would have been proper behavior if the URI had come from the command line rather the the homepage preference, but Firefox's guard on the origin of the URI was no longer compatible because of a method signature change. The fix updated the guard.
Summary: The fault was confined to an optional feature.
Firefox Bug 479994
Links: Bug Report, Fix Comment, and Fix Attachment
Explanation: One of the guards in the code for private browsing (an optional feature) checked the quitting flag instead of the
_quitting flag. In consequence the session created when Firefox was closed with the "X" button could not be restored.
Summary: The fault was confined to an optional feature.
Firefox Bug 529667
Links: Bug Report, Fix Comment, and Fix Attachment (with the test case made less fragile by the commits in comment 20 of bug 529922)