New in macOS Mojave, there's a NSBannerView (NSVisualEffectView) that gets inserted behind the actual cell view in each row marked as a Grouped Row. This is adding an unnecessary visual effect-view that ruins the already styled row for our purpose. How can I stop this new behavior? There's nothing in the docs to highlight the change.
Unfortunately it seems the only way around this is to subclass the NSTableRowView and override layout to explicitly mark the subview as hidden. Ugly, but works. the other non-solution is to unmark these rows as grouped, but then they no longer float, which isn't what I'm after. Here's the solution I follow: https://stackoverflow.com/a/52202620/3900270