Re: [Github-comments] [geany/geany] It is not possible to use Geany as a text editor if they want to edit (as plain text) Geany project file specified in command line. (#1658)
Ok, now I really finally got it. Always-working workaround:
geany some_existing_or_not_existing_file_with_very_strange_name_or_even_dir_name_or_project_name:0:00000
(Trailing zeros count should be enough to result does not match an existing file.)