The feature was added in October, but we have not had any builds of Natron since then, I have a Linux build available for crash testing, it has the latest version of the Text node if you want to test.
Release crashtest01 · rodlie/Natron · GitHub, you can use this build or copy Arena.ofx.bundle and use it on the latest RC release.
You can also build openfx-arena from source if wanted.