Created attachment 69845 [details]
This test fails:
Also happens for <span style="color:red">ب</span>ائعة, i.e. not cause by first-letter itself.
Probably related to, or even duplicate of 6148.
*** Bug 32414 has been marked as a duplicate of this bug. ***
Yes, this is a dup of bug 6148. We don't shape across inline box divisions. I expect doing so will be slightly tricky.
*** This bug has been marked as a duplicate of bug 6148 ***