I am almost ready to submit this.
Book details tool button. Note the addition of the menu triangle.
Book list context menu. It is now a sub-menu instead of an action.
Right click in the book details pane. It is now a submenu instead of an action.
Screen capture showing all three windows open (across two monitors). I tiled them.
The windows are non-modal always on top. Minimizing calibre will also minimize the book details windows. The windows are on top of calibre, but aren't forced to be on top of each other.
All the menu items can be assigned a shortcut.
Clicking on the toolbar button opens book details (same as old behavior)
Double clicking in the book details pane opens the book details windows (same as old behavior)