From 087d04db8e15a2a32b7c08387e4819e023b31133 Mon Sep 17 00:00:00 2001
From: Julian Smith <jules@op59.net>
Date: Wed, 2 Jun 2021 16:35:45 +0100
Subject: [PATCH] simgear/canvas/Canvas.cxx: Canvas::Canvas(): mark tree with
 VALUE_CHANGED_DOWN.

This is required for canvas to work - relies on value-changes being visible to
higher nodes.
---
 simgear/canvas/Canvas.cxx | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/simgear/canvas/Canvas.cxx b/simgear/canvas/Canvas.cxx
index 16504823..ca604077 100644
--- a/simgear/canvas/Canvas.cxx
+++ b/simgear/canvas/Canvas.cxx
@@ -137,6 +137,11 @@ namespace canvas
     _status(node, "status"),
     _status_msg(node, "status-msg")
   {
+    SG_LOG(SG_GENERAL, SG_ALERT, "Canvas constructor:"
+            " node=" << node->getPath(true /*simplify*/)
+            );
+    // Looks like we need to propogate value changes upwards.
+    node->setAttribute(SGPropertyNode::VALUE_CHANGED_DOWN, true);
     _status = 0;
     setStatusFlags(MISSING_SIZE_X | MISSING_SIZE_Y);