Non-intrusive and well integrated Rated 4 out of 5 stars

This extension has the right approach using a non-intrusive toolbar icon that provides simple graphical feedback, and more in-depth information when errors have occured. It feels like an appropriate form of integration for Firefox.

It would be great to see additional validation as well, particularly CSS validation, as well as having the errors listed in the popup dialog shown from the toolbar icon (in a more terse form) with the option of opening the validator's page in a tab afterwards.

Good work.

This review is for a previous version of the add-on (1.4.1).