Feedback continues:
* Took note from background colors
before and after the bug.
* In Preferences, Editor, there is no change (it's default, Background, System colors). Even after bug, Preferences are fine.
* With affected EasyCode still open, opened new instance: It does with normal colors.
What else:
* Just in case will keep bugged EasyCode opened (as it is hard to replicate problem). If you need any info let me know (ej. attach Ollydbg, look into memory, etc)

* Will make a simple experiment with very small project checking background colors. Who knows, maybe it's Windows Policies the problem's source.
Regards, Master.