At a low priority - certainly lower than the ObsTAP work - after review I have a few suggestions for tweaks to the ADQL entry screen UX.

1. Turn on (word) wrap, if possible, in the ADQL entry box, so that long auto-generated queries appear over multiple lines instead of extending off to the right of the text entry field. The current behavior is not very welcoming; if there are many specifically selected columns in the WHERE clause, the interesting substance of the query will be initially invisible, largely losing the initial benefit/impact of the new syntax highlighting.
2. When entering the ADQL-entry screen from the graphical query-builder screen for single-table queries, ensure that the ADQL-entry screen's schema browser is initialized with the branch for the selected table (from the query-builder screen) already open.