Thanks, I will review this shortly. Meanwhile, could you please look
at how Emacs with this patch displays some complex Emoji sequences?
Some of them look incorrect to me. For example, this sequence from
admin/unidata/emoji-zwj-sequences.txt:
1F469 200D 1F469 200D 1F467 200D 1F466 ; RGI_Emoji_ZWJ_Sequence ;
family: woman, woman, girl, boy # E2.0 [1]
(👩👩👧👦)
when displayed using Segoe UI Emoji, is shown with the "boy" part
overlapping the closing parenthesis, which looks incorrect to me.
"C-u C-x =" claims all of the codepoints of the sequence were composed
into a single grapheme cluster, but it doesn't look like that on
display, and the cursor doesn't include the "boy" part.