Enforce the widget/child realization/mapping invariants.

Enforce the widget/child realization/mapping invariants.

Sat Jul  7 02:50:14 2001  Owen Taylor  <otaylor@redhat.com>

	* gtk/gtkwidget.c (gtk_widget_set_parent): Enforce
	the widget/child realization/mapping invariants.

	* gtk/gtkwidget.[ch] gtk/gtkprivate.h: Add functions
	gtk_widget_[get/set]_child_visible() to control
	whether visible children of a mapped window are
	mapped.

	* docs/widget_system.txt: Updated for changes in
	container contract, and addition of GTK_CHILD_VISIBLE.

	* gtk/gtkcontainer.c: Add generic map()/unmap()
	functions that work for almost all containers.

	* gtk/gtknotebook.c gtk/gtkpacker.c: Use
	gtk_widget_set_child_visible() where necessary.

	* gtk/*.c: Remove excess map(), unmap(), and
	realization/mapping invariant enforcing code
	from many containers.