Improve GtkBox and GtkTable docs a bit

This adds some details gleaned from the tutorial, before its
impending demise.

docs/reference/gtk/tmpl/gtktable.sgml

@@ -22,8 +22,11 @@ convenient (but slightly less flexible) gtk_table_attach_defaults().
 To alter the space next to a specific row, use gtk_table_set_row_spacing(),
 and for a column, gtk_table_set_col_spacing().</para>
 <para>
-The gaps between <emphasis>all</emphasis> rows or columns can be changed by calling
+The gaps between <emphasis>all</emphasis> rows or columns can be changed by
-gtk_table_set_row_spacings() or gtk_table_set_col_spacings() respectively.
+calling gtk_table_set_row_spacings() or gtk_table_set_col_spacings()
+respectively. Note that spacing is added <emphasis>between</emphasis> the
+children, while padding added by gtk_table_atach() is added <emphasis>on
+either side</emphasis> of the widget it belongs to.
 </para>
 <para>
 gtk_table_set_homogeneous(), can be used to set whether all cells in the
@@ -169,6 +172,17 @@ specified by @left_attach, @right_attach, @top_attach and @bottom_attach.
 These each represent the leftmost, rightmost, uppermost and lowest column
 and row numbers of the table. (Columns and rows are indexed from zero).
 </para>
+<para>
+To make a button occupy the lower right cell of a 2x2 table, use
+<informalexample><programlisting>
+gtk_table_attach (table, button,
+                  1, 2, /* left, right attach */
+                  1, 2, /* top, bottom attach */
+                  xoptions, yoptions,
+                  xpadding, ypadding);
+</programlisting></informalexample>
+If you want to make the button span the entire bottom row, use @left_attach == 0 and @right_attach = 2 instead.
+</para>
 
 @table: The #GtkTable to add a new widget to.
 @child: The widget to add.

gtk/gtkbox.c

@@ -63,7 +63,10 @@
  * of the GtkBox are forced to get the same amount of space.
  *
  * Use gtk_box_set_spacing() to determine how much space will be
- * minimally placed between all children in the GtkBox.
+ * minimally placed between all children in the GtkBox. Note that
+ * spacing is added <emphasis>between</emphasis> the children, while
+ * padding added by gtk_box_pack_start() or gtk_box_pack_end() is added
+ * <emphasis>on either side</emphasis> of the widget it belongs to.
  *
  * Use gtk_box_reorder_child() to move a GtkBox child to a different
  * place in the box.
@@ -1256,9 +1259,9 @@ gtk_box_new (GtkOrientation orientation,
  * gtk_box_pack_start:
  * @box: a #GtkBox
  * @child: the #GtkWidget to be added to @box
- * @expand: %TRUE if the new child is to be given extra space allocated to
+ * @expand: %TRUE if the new child is to be given extra space allocated
- * @box.  The extra space will be divided evenly between all children of
+ *     to @box. The extra space will be divided evenly between all children
- * @box that use this option
+ *     that use this option
  * @fill: %TRUE if space given to @child by the @expand option is
  *     actually allocated to @child, rather than just padding it.  This
  *     parameter has no effect if @expand is set to %FALSE.  A child is