What you need to ask yourself is "Does anyone want yet another C++ editor?". There are lots of editors already out there, why do want to put the time and effort into something that has already been done multiple times?

For example, Qt Creator does what you want and is free.
Netbeans does what you want and is free, cross platform, and multi language.
CodeLite does what you want and is free.
Visual Studio Express does what you want and is free.
etc...

If you want specific features that other editors don't have, then implement them via plugins. No need to write yet another editor from scratch.