Settings dialog loses data and is unintuitive

[jblaine]

Description of the problem

Changed settings are not saved when you switch tabs in the settings dialog. You can't make a range of changes across all of the tabs and click "Apply" finally. This is unintuitive.

Steps to reproduce

1. Select settings
2. Type a value for Github username, for example
3. Do not click Apply.
4. Switch to another tab in the settings dialog
5. Switch back to the first one you edited in step 2. You will see your data's reverted for Github username

What you expected to happen

Something better than that...

Other data

Firefox latest stable release on Windows 10 as of this posting date.