JAL-48 patch NPE when encountering an alignment window on desktop which has not been...

diff --git a/src/jalview/gui/AlignFrame.java b/src/jalview/gui/AlignFrame.java
index a50e724..9818e6b 100755 (executable)
--- a/src/jalview/gui/AlignFrame.java
+++ b/src/jalview/gui/AlignFrame.java
@@ -880,7 +880,7 @@ public class AlignFrame extends GAlignFrame implements DropTargetListener,
         for (int i = 0; i < frames.length; i++)
         {
           if (frames[i] instanceof AlignFrame && frames[i] != this
-                  && ((AlignFrame) frames[i]).fileName.equals(fileName))
+                  && ((AlignFrame) frames[i]).fileName!=null && ((AlignFrame) frames[i]).fileName.equals(fileName))
           {
             try
             {