Nope. It is either way:
1) It's all good in Notepad++ (Cyrillic symbols), but upon loading the main.c file with OEM 866 encoding the Code::Blocks editor shows abracadabra (see the screenshot). Most importantly, the console shows correct symbols!
2) The Code::Blocks editor shows the Cyrillic right (within the code), but when I compile and run the console outputs abracadabra.
When I load the saved main.c file with OEM 866 encoding back into Code::Blocks the editor doesn't provide the Windows 866 encoding.
So, that's what I meant earlier. It is half the solution. What I need is to see nice and neat Cyrillic in the editor and the console app, not just in one of them. And as a perfectionist I'd prefer to get permanent solution to the problem, i. e. tweak something (the Windows registry, the Code::Blocks config file etc) so that I don't have to use the twisted approach suggested in the other two threads (include something [I don't understand fully] in every C project itself [no matter how small] that I run for self-education purposes). There's gotta be a solution, and I think it's very simple!