In CodeMirror, the setLineClass() is used to highlight the line of the cursor. This function was changed into addLineClass()/removeLineClass() (cf http://codemirror.net/doc/upgrade_v3.html#lineclass).

When porting the whole demo into 3.7_LTE, the setLineClass() was not ported.

We must investigate how setLineClass() translates into the new API, and port the demo code.