[RCD] Folders Manager re-design

I've no mockup, but I'll try to explain what changes in folders manager I'd like to provide.

1. UI: Add folder information/edition/creation frame on the right side

of the list. Remove bottom box for folder creation. Add list options menu buttons (like in addressbook groups box), where we'll have create, edit, delete action (and maybe other provided by plugins, e.g. to remove all messages in a folder)

2. Folders list: Make it slim. It means I'd like to have only folder

name (structured) and subscription checkbox. Drag-and-drop move supported. Would be nice to have quota indicator here too.

3. Folder frame: Here we'll have all information about a folder:

name, messages count, threading. The folder frame will provide new possibilities. I'd like to implement per-folder sorting setting. Maybe list_cols config could be also per-folder. It will be a good place to implement features like:

• ACL info/management
• displaying of folder size
• other provided by plugins