Does this actually work? Without even a `<st:adjunct …/>`?

I think you meant to use the `codemirror-mode` attribute as defined in the `<f:textarea>` tag. E.g.

    <f:textarea codemirror-mode="clike" codemirror-config="'onBlur': cmChange" value="…"/>

While you are at it, this code should be fixed to use the `field` attribute on `<f:entry>`, at which point `value` is superfluous, and a `doCheckFieldName` method can be added to the descriptor for a syntax check; just be sure to specify `checkMethod="post"` or else large scripts can overwhelm the web app container and produce weird errors.