JAL-3400 prevent duplications in View Chain menu

diff --git a/src/jalview/gui/StructureViewerBase.java b/src/jalview/gui/StructureViewerBase.java
index 77ba38d..1bb651a 100644 (file)
--- a/src/jalview/gui/StructureViewerBase.java
+++ b/src/jalview/gui/StructureViewerBase.java
@@ -1053,7 +1053,10 @@ public abstract class StructureViewerBase extends GStructureViewer
       repaint();
       return;
     }
-    setChainMenuItems(binding.getChainNames());
+    synchronized (chainMenu)
+    {
+      setChainMenuItems(binding.getChainNames());
+    }
 
     this.setTitle(binding.getViewerTitle(getViewerName(), true));