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.