Subject: edit a valuenode-valued waypoint doesn't trigger update of parent

Example: ~chris/Desktop/anim/dynamic-waypoints.sifz

set preview quality to 1 (best) and the time to be 5s
edit the 'left rate' child node to be 1 instead of 0.
the workarea doesn't reflect any change.
move the time slider away from 5s and back to 5s.
the workarea now reflects the change.

Usually when a node is edited, the on_changed() methods cause all
ancestors of the node to update themselves, but waypoints don't
inherit from Node, and so don't have the concept of a parent_set to
update when changed.

The use of valuenodes as the value of waypoints is unusual in synfig,
but the addition of bones makes it more common, since re-parenting
causes the use of valuenode waypoints.

Example: ~chris/Desktop/anim/bones/test2.sifz

Select either of the 'anim' layers, edit the bone ducks, note that
nothing gets updated.

------------------------------------------------------------------------
dooglus, Fri Jan  2 14:27:07 CET 2009

a simple recipe:

1. new document, make a circle, export the radius as 'r' ('r' is a ValueNode_Const)
2. disconnect the radius, switch to animate edit mode, edit the radius, creating a waypoint
3. in the Children tab, select 'r'
4. in the Timetrack tab, right-click the waypoint
5. 'connect' (the waypoint now has a ValueNode_Const value)
6. switch out of animate edit mode
7. in the Children tab, edit the value of 'r'
8. watch the circle's radius fail to change
9. slide the time slider, and see the radius change

------------------------------------------------------------------------
dooglus, Fri Jan  2 21:03:37 CET 2009

Here's a patch that fixes the bug for the exact recipe above, but it
must miss lots of similar cases.  The problem is that there's code
spread all over that can add and modify waypoints.  We need a single
function that does it, so we can make sure the parent_set is kept
correctly up to date:

diff --git a/synfig-studio/trunk/src/synfigapp/actions/waypointconnect.cpp b/synfig-studio/trunk/src/synfigapp/actions/waypointconnect.cpp
index f86cc1e..9b304a6 100644
--- a/synfig-studio/trunk/src/synfigapp/actions/waypointconnect.cpp
+++ b/synfig-studio/trunk/src/synfigapp/actions/waypointconnect.cpp
@@ -134,6 +134,7 @@ Action::WaypointConnect::perform()
 
 	old_value_node=iter->get_value_node();
 	iter->set_value_node(new_value_node);
+	iter->get_parent_value_node()->add_child(new_value_node.get());
 
 	/*set_dirty(true);