Find a replacement for GEmblemedIcon with GTK 4
We use emblems for marking files with insufficient file permissions, symbolic links, etc. We even allow extensions to add more emblems.
The way the emblems are currently implemented is that we wrap the file icon/thumbnail in a GEmblemedIcon which defines a list of emblem names, and GTK 3 handles the rest. The application has no control nor knowledge of which emblems are actually rendered and how.
This architecture has been the source of multiple tricky bugs: #912 (closed), #1189 (closed), #1226 (closed), #1506 (closed).
GTK 4 doesn't offer support for rendering GEmblemedIcon (gtk#2374 (closed)), so we need to figure out a new solution.
With the new list model-based view widgets, I believe we can easily overlay emblem icons as either widgets (through GtkOverlay) or render nodes (through the GtkSnapshot API).
However, as long as we use GtkTreeView as the base for our list view, neither of these is an option and we may need to implement a custom GtkCellRenderer.