Comment 48 for bug 27867

If the problem is from outside FF, then I do not believe it is an issue of pleasing everyone. We should never try to appease those who use non-standard ways of doing things. If any people do not conform to W3C standards, they are actually part of the problem.

We can try to educate, but the software must conform. The more that all browsers conform, the less we will have weirdo behavior from those like IE.

With that said, the best way is always to re-write code to do what was requested in the first post. However, if the text is actually an image, then an error message that simply states that fact will go a long way to user understanding of the problem others create. No text to adjust will give no adjustment. That's just the way it is. Besides, that is reasonable.

Bottom line, FF should give feedback by way of explanation.