Created attachment 183962 [details] A few examples of diacritics overlapping previous-line contents The handling of (Arabic) diacritics is such, that in some cases and with some fonts, diacritics from one line intersect/overlap content from another line - either diacritics or actual characters. One example of this is the relatively-popular Arabic font family KacstBook, which is even under consideration for being our default Arabic body font (see issue 150481): Diacritics over an aleeph - a tall letter - easily interfere with the previous line, in different scenarios and with different language nad font choices for the previous line. The attached document exemplifies this for a few cases. (The text doesn't make sense, think of it as gibberish; I only used it to get certain things to align.)
This a font bug, the marks are placed so high they exceed the line ascender and go into the above line.
(In reply to خالد حسني from comment #1) > This a font bug, the marks are placed so high they exceed the line ascender > and go into the above line. Ok, sure, but don't we have logic to dynamically determine how high a line needs to be based on the characters it actually has? ... hmm. On second thought, maybe that might not be such a great idea, because it would make line heights non-uniform in a paragraph. Well, ok, never mind.