What is the best and safest way to place an Arabic Shaddah (ّ = \u0651 = "ARABIC SHADDA") over a Hebrew letter?
Hebrew textbooks for colloquial Arabic need to place the Shaddah over a letter. This was done in pre-Unicode days, so either fonts were hacked to have this, or else metal glyphs were placed together (in the days of manual typesetting). Unicode, however, doesn't make it easy to position diacritical marks from one language on top of characters from another language.
I'm looking for the best way of doing this in the Unicode standard.