I left in a hurry. I forgot to say thanks. I would never have found that RichEdit code. I didn't even know that there was a RichEdit unit in Lazarus.
"richedit" unit comes with FreePascal, rather than Lazarus. It's a part of standard WinAPI interface.
Unfortunately, however, it only works with the paragraph being RTL. If it isn't RTL it will make it RTL. So you can't do inline quotes from Hebrew within an English paragraph. You would only be able to that by copy/paste.
A bit more details:
I's possible to inline Hebrew characters into English paragraph. These characters would look and behave nicely. However, punctuation between these characters would act as if it's left-to-right punctuation.
That's a problem, because it
should use surrounding (hebrew) letters as a direction, rather than text (or paragraph) left-to-right direction.
The fact, that a pasted text acts as expected, makes me think that it should be possible to make entered punctuation to work properly.
It also seems that
RIGHT-TO-LEFT EMBEDDING (U+202B)
and
RIGHT-TO-LEFT OVERRIDE (U+202E)
are accepted (they act as an invisible character), but ignored and do not affect the entered text.