[gtk+] Added documentation to gtksizegroup.sgml explaining what happens with height-for-width widgets.

[Tristan Van Berkom <tvb src gnome org>]

commit 266476d32bd269461916703a6d90d910f9221b8d
Author: Tristan Van Berkom <tristan van berkom gmail com>
Date:   Wed Sep 15 03:54:12 2010 +0900

    Added documentation to gtksizegroup.sgml explaining what happens with height-for-width widgets.
    
    When grouping height-for-width trading widgets (wrapping labels for instance)
    vertically; the height for the minimum width will always be used for the entire
    group... this patch warns about this in the docs.

 docs/reference/gtk/tmpl/gtksizegroup.sgml |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)
---
diff --git a/docs/reference/gtk/tmpl/gtksizegroup.sgml b/docs/reference/gtk/tmpl/gtksizegroup.sgml
index 4bf90ce..4d6329f 100644
--- a/docs/reference/gtk/tmpl/gtksizegroup.sgml
+++ b/docs/reference/gtk/tmpl/gtksizegroup.sgml
@@ -44,6 +44,15 @@ vertical size from the vertical requisition of all widgets that can be
 reached from the widget by a chain of size groups of type
 %GTK_SIZE_GROUP_VERTICAL or %GTK_SIZE_GROUP_BOTH.
 </para>
+<para>
+Note that only non-contextual sizes of every widget are ever consulted
+by size groups (since size groups have no knowledge of what size a widget
+will be allocated in one dimension, it cannot derive how much height
+a widget will receive for a given width). When grouping widgets that
+trade height for width in mode %GTK_SIZE_GROUP_VERTICAL or %GTK_SIZE_GROUP_BOTH: 
+the height for the minimum width will be the requested height for all 
+widgets in the group.
+</para>
 <refsect2 id="GtkSizeGroup-BUILDER-UI">
 <title>GtkSizeGroup as GtkBuildable</title>
 <para>