avoid GTK packing warning when using >1 backend

diff --git a/gtk2_ardour/engine_dialog.cc b/gtk2_ardour/engine_dialog.cc
index d438ff83270e5d2948ff53ed76564a63592fa1ec..8cd0473c085df0f866c1005b1667700463af3317 100644 (file)
--- a/gtk2_ardour/engine_dialog.cc
+++ b/gtk2_ardour/engine_dialog.cc
@@ -327,6 +327,10 @@ EngineControl::EngineControl ()
         Gtkmm2ext::container_clear (basic_vbox);
         Gtkmm2ext::container_clear (basic_packer);
 
+        if (control_app_button.get_parent()) {
+                control_app_button.get_parent()->remove (control_app_button);
+        }
+
         label = manage (left_aligned_label (_("Audio System:")));
         basic_packer.attach (*label, 0, 1, 0, 1, xopt, (AttachOptions) 0);
         basic_packer.attach (backend_combo, 1, 2, 0, 1, xopt, (AttachOptions) 0);