I'm not convinced this isn't a GTK+ bug. GTK+ changed so that if you modified the foreground color of a parent GtkEventBox, a child GtkEventBox also now get that same foreground color (before, they didn't). But the background isn't treated the same way (i.e. the behavior of not inheriting the color stays the same). Seems wrong. But I worked around it in Deja Dup.
I'm not convinced this isn't a GTK+ bug. GTK+ changed so that if you modified the foreground color of a parent GtkEventBox, a child GtkEventBox also now get that same foreground color (before, they didn't). But the background isn't treated the same way (i.e. the behavior of not inheriting the color stays the same). Seems wrong. But I worked around it in Deja Dup.