X-Git-Url: http://source.jalview.org/gitweb/?a=blobdiff_plain;f=src%2Fjalview%2Fstructure%2FStructureSelectionManager.java;fp=src%2Fjalview%2Fstructure%2FStructureSelectionManager.java;h=8d684c1d598b8f0590541c987a94dd43797d78b0;hb=6b1d4e765d7a6beafcc1eb1fec38e041f3fb780f;hp=741571210680f2c4b334d23553db31fd2f860892;hpb=a3fc7900ca2fd44261167a99f9ab2a0e85ea7aae;p=jalview.git

diff --git a/src/jalview/structure/StructureSelectionManager.java b/src/jalview/structure/StructureSelectionManager.java
index 7415712..8d684c1 100644
--- a/src/jalview/structure/StructureSelectionManager.java
+++ b/src/jalview/structure/StructureSelectionManager.java
@@ -53,13 +53,25 @@ public class StructureSelectionManager
   }
 
   Hashtable mappingData = new Hashtable();
-
+  private static StructureSelectionManager nullProvider = null;
   public static StructureSelectionManager getStructureSelectionManager(
           StructureSelectionManagerProvider context)
   {
-    if (context==null)
-    {
-      throw new Error("Implementation error. Structure selection manager's context is 'null'", new NullPointerException("SSM context is null"));
+    if (context==null) { 
+      if (nullProvider == null)
+      {
+        if (instances != null)
+        {
+          throw new Error(
+                  "Implementation error. Structure selection manager's context is 'null'",
+                  new NullPointerException("SSM context is null"));
+        }
+        else
+        {
+          nullProvider = new StructureSelectionManager();
+        }
+        return nullProvider;
+      }
     }
     if (instances == null)
     {
@@ -68,7 +80,13 @@ public class StructureSelectionManager
     StructureSelectionManager instance = instances.get(context);
     if (instance == null)
     {
-      instances.put(context, instance = new StructureSelectionManager());
+      if (nullProvider!=null)
+      {
+        instance = nullProvider;
+      } else {
+        instance = new StructureSelectionManager();
+      }
+      instances.put(context, instance);
     }
     return instance;
   }