With the latest change to v0.29.1 the MenuSelectWidget seems to have lost (parts of) its onKeyDown handling, the "escape" key does not close the suggestion menu as before.
This behavior can be reproduced on the demo page. Typing any value, e.g. "asd" in the ComboBoxInputWidget field (selects the first value), then hitting escape - this does not close the menu as observed in earlier versions (e.g. v0.28.2).
This can be reproduced in both latest Firefox and Chromium.
The defective code is not immediately obvious to me but was introduced during https://gerrit.wikimedia.org/r/c/oojs/ui/+/437960
Background: We first experienced this in a browser test for WikibaseLexeme on Special:NewLexeme when specifying a fallback lemma language (initially hidden), worked around it by not using escape any more.