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Can you send me a screenshot and an example file to support@textasticapp.com so I can see the problem?
Actually, it just looks at the previous line when you press enter and inserts the same amount of tabs and spaces in the new line.

I plan to make this more sophisticated in a future version. For example, it should increase the indent level when entering "{" in C code.
It's really great to hear that Japanese works for you now! Thanks to the wonders of Core Text :)
Oh, damn - I forgot the replace text field - I put it on my todo list :)