I'm not too keen on trying to integrate the spell checker into the text editor, for the following reasons:
- The text editor has it's own syntax coloring mechanism that will likely interfere with the spell checker (same kind of API to hook into the text components)
- The text editor is a developer tool, not an end user tool, like your skin's UI is. A developer primarily uses it for code, not text
Now, for translations, which are also edited in this text editor, this would be far more beneficial, but again, I suspect integration clashes coming up as the text editor has this syntax highlighting mechanism.