I'm not specifically talking about editing a source file that contains a NUL character. I'm talking about not being able to quickly peek at just any file and this is where Geany is limited (read only would have been enough for me). Geany refuses to open files that it does not recognize and this is what I call limiting. NotePad++ under Windows opened ANYTHING and never complained about not being able to recognize the file format or the language. It would display anything as plain text, even binary files.

I'm well aware of other utilities for this kind of job such as hex editors (which I also have) but I like to be able to quickly peek at files without switching apps when I'm working in an IDE. Kate under macOS looks to be a closer replacement to NotePad++ as it not only lets you open any (binary or whatever) file you want, but it also has a "Find in files" function, which I could not find in Geany unfortunately.

Thanks again for trying to help and good luck with Geany.