add _gtk_tree_view_column_get_focus_area().

add _gtk_tree_view_column_get_focus_area().

2007-03-20  Kristian Rietveld  <kris@gtk.org>

	* gtk/gtktreeviewcolumn.c:
	* gtk/gtktreeprivate.h: add _gtk_tree_view_column_get_focus_area().

	* gtk/gtktreeview.c (gtk_tree_view_clamp_column_visible): add
	focus_to_cell parameter, rework to handle clamping columns which
	are bigger than the available page size better,
	(gtk_tree_view_key_press): remove code handling moving the focus
	to other column headers,
	(gtk_tree_view_header_focus): add clamp_column_visible parameter,
	fix RTL support, don't wrap around when moving focus to other
	column headers, call gtk_tree_view_clamp_column_visible() instead
	of duplicating code,
	(gtk_tree_view_focus): only clamp the column visible when we are
	explicitly moving to another column header (fixes #399555, Charles
	Kerr),
	(gtk_tree_view_move_cursor_left_right): update call to
	gtk_tree_view_clamp_column_visible().

svn path=/trunk/; revision=17546