[HarfBuzz] Order of combining diacriticals

[Eli Zaretskii]

In Emacs, we use HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES cluster
level, because HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS produced
incorrect display.  With this level, whenever I type a Hebrew base
character with more than one diacritical, I need to type them in
certain order, otherwise the display is incorrect.

For example, in this series of characters:

  U+05D1 HEBREW LETTER BET
  U+05B0 HEBREW POINT SHEVA
  U+05BC HEBREW POINT DAGESH

I need to type them in the above order; if I type DAGESH before SHEVA,
the produced display is incorrect.

Is this expected with level-0 clusters?  Or should I look for a bug in
how Emacs uses HarfBuzz?

Thanks.