Introduce an annotation subclass which can carry additional style info and a tree table cell which can render it.
Use a trick to get the Annotation from the renderer so that the column type can be the actual object type.
Editor for the style column.
Custom colours for group annotations too.
Stick to "color" when used in code.
Fixed issue where it wouldn't repaint the cell when switching from custom back to default.
Size tweak to the popup for editing annotation style.
More annotations