20 years ago i wrote code for farsi (aslo BIDI) text editor without using LTR or RTL character, realy no need !!
only selected language key is enough to Implement editor adding new input character to left of current word or right side it ,
Tis editor working well
the same Procedure can be using for writing editor for unicod character ....
ByUnicode a Complex algorithms designed ,to write sentences in Persian and Latin,it is very difficult,actually impossible adding latin word inside farsi sentence ,because:
Definitions according to the algorithm, location the word is automatically moved !! (for keeping algorithm)
It is Not correct
Maning of sentence is change or will be meaningless...
why did this ?,Unide should design an algorithm according keeping location of words in the sentence, No need change location
Unicode and ANSI only advantage in the form of letters in words, this advantage does not relate to the word in the sentence (at least in Persian and Arabic)
string in the microsoft environment is immutable ,why?,i think only word in string should be immutable ,with this deisgn left right and mid function not work on string