According to the documentation for NSView's drawRect:
If your app manages content using its layer object instead, use the updateLayer method to update your layer instead of overriding this method.
I have an NSView with subviews that are provided by the framework, and they all draw using drawRect:. This framework-provided view is a subview of an NSView for which I require a layer. Because my framework-provided view is a descendant of a layer-backed view, drawRect: isn't usually called, especially in cases where the window is made active or inactive (the view needs to update to reflect its (in)active state).
Of course if I make my containing view not layer backed, updates occur when the window is made active or inactive.
Without modifying the framework into a custom fork, what's the best avenue for making sure drawRect: occurs when needed in my framework-provided view?
Thanks.
Edit 25-Aug-2018:
It looks like the trick is to set one of the views in the hierarchy to, e.g., [view setCanDrawSubviewsIntoLayer:YES, which according to the documentation uses all of the subviews’ drawRect: to add their drawing to its own layer. However this seems to work only through 10.13, and is broken in the 10.14 beta. I'll continue to look for a potential API change, unless this is a 10.14 beta bug.
Since the issue is still unresolved, it's not really answered yet.
Layer-backed views which don't override -wantsUpdateLayer to return true still draw themselves using -drawRect:. The bit of documentation you quoted is using "should" to mean "should, for best performance,". It's not required, it's just recommended.
Views don't generally redraw themselves just because the containing window has changed key or main status. You would have to mark them as needing display. Or the framework should be doing that.
I suspect the reason that it works when your view is not layer-backed is that you are marking your view as needing update. Since non-layer-backed views draw into the window's backing store using the painter model (back to front), if your view redraws itself then any subviews will have to redraw themselves on top of your view's drawing.
If the framework's views need to redraw when the window's key/main status changes, then they should be observing the relevant notifications and setting themselves as needing display. If they're not doing that, it's a framework bug. You can work around it by marking them as needing display yourself.