Icons and Content Customization

RibbonIconPresenter is the theme-facing control that unifies these icon sources:

raw icon content,
resource keys,
Fluent path data strings,
emoji,
overlay badges and overlay counts.

Common customization points:

IconPathData, IconEmoji, OverlayPathData, OverlayEmoji
icon sizing and stretch properties
top-bar and header content slots on Ribbon
HeaderContent and FooterContent on RibbonBackstage

This model lets you keep the ribbon chrome consistent even when individual commands need badges, alternate icons, or application-defined content blocks.