Only draw the column that is exposed.

Only draw the column that is exposed.

Fri Feb 23 17:50:13 2001  Jonathan Blandford  <jrb@redhat.com>

	* gtk/gtktreeview.c (gtk_tree_view_bin_expose): Only draw the
	column that is exposed.

	(_gtk_tree_view_update_size): Changed name from set_size, and
	changed function to do more work, and not force people calling it
	to figure out the size.  Simplifies a lot of code elsewhere.