Month input — a month and a year, no day

Expected: the first control shows September 2026 and its picker offers months and years but no days. The empty control opens on the current month. Cancel restores the original; OK keeps the choice. The value is yyyy-mm.

Bounds

Expected: only June to December 2026 can be chosen in the first control; the second steps by quarter (every third month from March 2026).

Readonly, disabled and invalid values

Expected: readonly and disabled open nothing. The invalid values are sanitised to empty.