I agree that most common code is done in ANSI. There are some tools that support files in Unicode (MSVC 2005 for example).
But anyways, you appart from the ability of writing source code, with the IDE can edit resources or plaint text files (which are commonly only in ASCII if they're written english, all other languages are better off with Unicode).
The world is towards Unicode, so I can guess in 10 years everything will be in Unicode.
But, all of that, it's not the main reason of why Code::Blocks is in Unicode.
It was made Unicode compliant because most linux distros now only distributes binary packages of wxWidgets in Unicode mode, not ASCII mode.
BTW, you can compile if you want wxWidgets in ASCII mode, so C::B will be in ASCII mode too (but fear that in some distant future... ASCII will be something of the past
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