I would like to be able to add three buttons (text align left, text align justify, text align right).

Is this possible with the current version of trix?

Is there anyway to pass a class to a blockAttribute?

All I was able to do, was add a new textAttribute that has a custom tagName, which I can then style through CSS (display: block; text-align: justify;).

Trix.config.textAttributes.textAlignJustify = { tagName: 'div-text-align-justify' }

The problem with custom HTML tags is browser support. Because although it's defined in HTML 5, only Chrome (and Opera) provide support.

Thanks!