4 - Implement 'rand' feature.
10 - API to accept a list of languages?
12 - Remove hb_ot_shape_glyphs_closure()?
18 - Language to/from script.
22 - Add sanitize API (and a cached version, that saves result on blob user-data)
24 - BCP 47 language handling / API (language_matches?)
26 - Add hb_font_create_unscaled()?
28 - Add query / enumeration API for aalt-like features?
30 - Add segmentation API
32 - Add hb-fribidi glue?
35 hb-view / hb-shape enhancements:
36 ===============================
38 - Add --width, --height, --auto-size, --ink-box, --align, etc?