Plain Text Linker by Marnes

Available for Chrome too.

Functionality
When you double-click on a piece of plain text, Plain Text Linker tries to determine if what you clicked could be a URL and tries to open it. Try it!

Usage notes

• there's an option to require shift-doubleclick for a link to be opened, so you can still doubleclick URLs without anything happening
• you can choose if links should open in the foreground or background by default, and holding the Ctrl key will invert this behavior

The Options screen will automatically open after add-on updates if they force a change to any of your settings.

Please rate/review/donate! :)
A lot of time and work goes into creating my addons, and making changes or troubleshooting issues for users.

Problem, bug, broken, question, request?
Please use the linked support site or email for all non-review communication. AMO policy protects both users and developers by demanding certain quality standards from addons as well as reviews. Severely disfunctional addons are not published. Reviews and ratings must consider the entire addon, set reasonable expectations, and be timeless: a bad rating focusing solely on a systemic bug or on a problem not suffered by other users will stay long after the issue is resolved. AMO also gives extremely limited communication abilities, so contacting me properly will get your issue resolved much better and faster.