Photoshop CS4 has the ability to edit existing Arabic text layers. Due to technical reasons, the functionality as it is in CS4 can only be exposed if you already have an Arabic text layer created. If you’d like to create Arabic text layers, you can start with this template that we have provided containing a single type layer from which you can edit (type layer contains font type that support ALL languages).
ArabicTemplate_PSCS4.zip for Photoshop CS4/Windows
Open the template in Photoshop CS4. Select the existing text on the type layer of the template and replace it with the Arabic you want. Using this template, you can now cut, copy, and paste between applications without destroying your text flow. Also works with all other languages supported by Photoshop, such as Japanese, Chinese, Korean, Greek, Cyrillic, etc. NOTE: Be sure to have your Arabic input method(s) enabled on your OS.