Support entry tags
Submitted by Cosimo Cecchi
libgd has a popular GtkEntry subclass (GdTaggedEntry) that allows for adding tags to it. It is desirable to have that supported in GTK proper.
One current limitation of GtkEntry is that, since it's not a GtkContainer, it can't have child widgets. That means that in the current implementation tags are not widgets.
I am not sure this is a limitation that can be fixed before GTK 4; in such case I would propose that we use the current implementation for the time being.