just some more background:
That's the perl module (imports as Bio:: IIRC). It allows accessing the database and remote controlling ARB. It's build with makemaker and can be finicky to build, plus it's dependent on perl ABI. ARB's macro recording feature writes Perl files, and a number of menu items are written in Perl (CSV import for example). In a perfect world, this would go into an ARB perl module. It has a namespace issue, though, as it occupies "Bio::". Since user recorded macros use that name space, it's not easy to fix that legacy issue.
That's the ARB Window Toolkit, so the high level components of the kit interfacing with the libARBDB for various things, e.g. Redo/Undo stack.
That's the lower level part of the window toolkit sitting on top of motif and X11.