Created attachment 263768 [details] [review]
Set title on titlebox if titlebar isn't set

Not sure this is right - seems weird - but also seems to kinda work.

I don't think that's right. If the headerbar is app-provided, they should deal with it themselves, instead of indirectly relying on GtkWindow to do something behind the scenes.

Hmm, that's pretty awkward for most apps though. It is pretty easy to get at the toplevel window from any point in the code but getting at the headerbar isn't. If we want to do this maybe we should have a gtk_window_get_titlebar.

I don't think 

gtk_widget_class_bind_template_child_private (YourClass, headerbar)

is hard.

I'm not sure what the objection is here. But it is just nasty that gtk_window_set_title inexplicably does nothing when we're using CSD - some of the time and some of the time it works. At the very least this should be explained in the docs.

I don't know. Maybe it is harmless enough to allow this. But I still think it is somewhat odd to set a custom titlebar, and then have manipulated behind the scenes by the toolkit.

Yeah, if you set up a custom title widget in headerbar I'd expect that to override the plain text title. It does get a little icky when you have the ability to set each independently - say, setting both a title property on the window and the headerbar in glade.