JAL-574

diff --git a/src/jalview/gui/AlignViewport.java b/src/jalview/gui/AlignViewport.java
index ff21931..35743ab 100755 (executable)
--- a/src/jalview/gui/AlignViewport.java
+++ b/src/jalview/gui/AlignViewport.java
@@ -2014,32 +2014,34 @@ public class AlignViewport implements SelectionSource, VamsasSource
   /**
    * checks current SelectionGroup against record of last hash value, and
    * updates record.
+   * @param b update the record of last hash value
    * 
-   * @return true if SelectionGroup changed since last call
+   * @return true if SelectionGroup changed since last call (when b is true)
    */
-  boolean isSelectionGroupChanged()
+  boolean isSelectionGroupChanged(boolean b)
   {
-    int hc = (selectionGroup == null) ? -1 : selectionGroup.hashCode();
-    if (hc != sgrouphash)
+    int hc = (selectionGroup == null || selectionGroup.getSize()==0) ? -1 : selectionGroup.hashCode();
+    if (hc!=-1 && hc != sgrouphash)
     {
-      sgrouphash = hc;
+      if (b) {sgrouphash = hc;}
       return true;
     }
     return false;
   }
 
   /**
-   * checks current colsel against record of last hash value, and updates
+   * checks current colsel against record of last hash value, and optionally updates
    * record.
-   * 
-   * @return true if colsel changed since last call
+
+   * @param b update the record of last hash value
+   * @return true if colsel changed since last call (when b is true)
    */
-  boolean isColSelChanged()
+  boolean isColSelChanged(boolean b)
   {
-    int hc = (colSel == null) ? -1 : colSel.hashCode();
-    if (hc != colselhash)
+    int hc = (colSel == null || colSel.size()==0) ? -1 : colSel.hashCode();
+    if (hc!=-1 && hc != colselhash)
     {
-      colselhash = hc;
+      if (b) {colselhash = hc;}
       return true;
     }
     return false;