AbsoluteTelnet supports the full Unicode Bidirectional Algorithm as well as combining characters and Arabic shaping.  Support for Bidirectional text and Arabic shaping is provided by the GNU Fribidi library maintained by Behdad Esfahbod at fribidi.org.

RTL support is disabled by default.   You can enable it through the RTL button on the toolbar.  RTL support increases the amount of processing required to display text on the screen and should be left disabled unless needed.
AbsoluteTelnet supports combining characters and bidirectional text, as can be seen in this sample of Yiddish text.
Absolute also supports  Arabic text shaping as can be seen here.