Given the discussion here, it seems there's a clear need for a text-editor that's cross-platform, fast (like ST, unlike Atom), open-source (like Atom, unlike ST), very configurable (like Atom and ST), easily extensible (like Atom) and easy to use/grasp for an user accustomed to typical windows applications (like Atom and ST, unlike vim and emacs).

Seems to be something like this could be done using QScintilla. Qt would give it an excellent cross-platform support, Scintilla a good editor with a speed of C++, and the ease of development and extensibility would be possible thanks to either PyQt (Python) or QtQuick (JavaScript). Just a thought...