Hi

Is it possible in custom layouts to edit custom fields (such as my 2 custom rating fields) without opening song properties or to add the moods field to the right click menu?

Hi, for custom rating fields, with a custom layout, you can edit them the same way you edit the normal rating (with the stars pictures) by adding these widgets : Stars2(field=FIELD_ID1) Stars3(field=FIELD_ID2), where FIELD_ID is the field id of those custom rating field.
Though currently the stars picture will be the same for all the rating field, I'm going to add an option to change it.

About adding submenus to edit custom ratings, moods and other label-like fields, you can't currently. But it was only lacking a few things, so you'll see a commit soon, I'll reply when I it's done.

Forgot to reply, I've committed the changes a week or two ago.

Now all the genre/label-like fields have an option to have an edit submenu. It's on by default for labels, and off by default for genres/mood/... (as they require writing the tags)
Also, you can now choose the stars images for each rating field, you can add custom ones in ~/.config/gmusicbrowser/icons/