I have just purchased the Mac App Marked for the princely sum of £2.69 from the Apple Store, and I am now putting it through its paces for the first time.
I chose TextWrangler to write this first file for no other reason than I have not used it for some time as I use Taco HTML Edit to write my HTML files.
Soft Wrap Text in Text Wrangler
I tried to set this using Preferences but it did not seem to make any difference. I then discovered that it is also set in Text Options* in the Edit menu which overrides the preferences.