Instead of using 1 global queue for both resizes and style validation, use 2 queues. This makes the code a lot simpler and fixes a bug where we could accidentally stop restylying for very delayed restyles.
GtkContainer::need_resize and GtkWidget::alloc_needed are the same thing.
- Ensure arrow button is always included - Invalidate list when direction changes
https://bugzilla.gnome.org/show_bug.cgi?id=651707