more const value_as_string fixes

diff --git a/libs/ardour/pannable.cc b/libs/ardour/pannable.cc
index ebf3115658c927278b976fecf2690651fd51c89f..754e8fc5d25f4f7dde879b5e0d3e9cc6895410c0 100644 (file)
--- a/libs/ardour/pannable.cc
+++ b/libs/ardour/pannable.cc
@@ -275,7 +275,7 @@ Pannable::set_state (const XMLNode& root, int version)
 }
 
 string
-Pannable::value_as_string (boost::shared_ptr<AutomationControl> ac) const
+Pannable::value_as_string (boost::shared_ptr<const AutomationControl> ac) const
 {
        boost::shared_ptr<Panner> p = panner ();