The update of the needs-attention state is done via its own property,
so it doesn't need to be done via visibility changes.
This patch is largely the result of inspecting the code due to a warning
and not a result of testing. So if issues pop up that bisect back to
this patch, that's why.
The GtkStack and GtkStackSwitcher code did not really
follow GTK+ conventions for includes. Fix that, and also
fix up a case of gpointer vs gpointer* confusion
in gtkstack.c.
The child property is watched by the StackSwicther which in turns sets a
needs-attention css class on the corresponding button, so that the theme
can for instance show a throbbing animation if one of the hidden pages
needs the user attention.
https://bugzilla.gnome.org/show_bug.cgi?id=707153
Add separate GtkStack and GtkStackSwitcher widgets that are an
alternative to GtkNotebook. Additionally, GtkStack supports
animated transitions when changing pages.
These widgets were initially developed in libgd.
