From d0a4b94941ae548533854c025e250c53144f2b93 Mon Sep 17 00:00:00 2001
From: Katja Luther <k.luther@bgbm.org>
Date: Mon, 16 Nov 2015 14:31:12 +0100
Subject: [PATCH] fixing #4808

---
 .../DescriptionElementDragListener.java       |  8 +++-
 .../DescriptionElementDropAdapter.java        | 44 ++++++++++---------
 2 files changed, 30 insertions(+), 22 deletions(-)

diff --git a/eu.etaxonomy.taxeditor.editor/src/main/java/eu/etaxonomy/taxeditor/editor/view/descriptive/DescriptionElementDragListener.java b/eu.etaxonomy.taxeditor.editor/src/main/java/eu/etaxonomy/taxeditor/editor/view/descriptive/DescriptionElementDragListener.java
index e5e58d0f6..86c95a2c1 100644
--- a/eu.etaxonomy.taxeditor.editor/src/main/java/eu/etaxonomy/taxeditor/editor/view/descriptive/DescriptionElementDragListener.java
+++ b/eu.etaxonomy.taxeditor.editor/src/main/java/eu/etaxonomy/taxeditor/editor/view/descriptive/DescriptionElementDragListener.java
@@ -61,7 +61,9 @@ public class DescriptionElementDragListener extends DragSourceAdapter {
 		List<DescriptionElementBase> descriptionElements = new ArrayList<DescriptionElementBase>();
 		for (Object object : selection.toList()){
 			if(object instanceof DescriptionBase){
-				descriptionElements.addAll(((DescriptionBase) object).getElements());
+				if (!((DescriptionBase) object).getElements().isEmpty()){
+					descriptionElements.addAll(((DescriptionBase) object).getElements());
+				}
 				description = HibernateProxyHelper.deproxy(object, DescriptionBase.class);
 				
 			}else if(object instanceof FeatureNodeContainer){
@@ -73,7 +75,9 @@ public class DescriptionElementDragListener extends DragSourceAdapter {
 		}
 		if (DescriptionElementTransfer.getInstance().isSupportedType(
 				event.dataType)) {
-			event.data = descriptionElements.toArray(new DescriptionElementBase[descriptionElements.size()]);
+			if (!descriptionElements.isEmpty()){
+				event.data = descriptionElements.toArray(new DescriptionElementBase[descriptionElements.size()]);
+			}
 			
 		}
 		
diff --git a/eu.etaxonomy.taxeditor.editor/src/main/java/eu/etaxonomy/taxeditor/editor/view/descriptive/DescriptionElementDropAdapter.java b/eu.etaxonomy.taxeditor.editor/src/main/java/eu/etaxonomy/taxeditor/editor/view/descriptive/DescriptionElementDropAdapter.java
index 9af171323..e7d7f2907 100644
--- a/eu.etaxonomy.taxeditor.editor/src/main/java/eu/etaxonomy/taxeditor/editor/view/descriptive/DescriptionElementDropAdapter.java
+++ b/eu.etaxonomy.taxeditor.editor/src/main/java/eu/etaxonomy/taxeditor/editor/view/descriptive/DescriptionElementDropAdapter.java
@@ -52,30 +52,34 @@ public class DescriptionElementDropAdapter extends ViewerDropAdapter {
 		boolean isCopy = getCurrentOperation() == DND.DROP_COPY ? true : false;
 		
 		// cannot drop a feature node onto itself
-		for (Object droppedElement : droppedElements) {			
-			if (droppedElement == null){
-				MessagingUtils.warningDialog("Operation not supported yet", this, "We are currently unable to drag and drop a newly created element. Please save the editor to make this work.");
-				return false;
-			}
-			if(! (droppedElement instanceof DescriptionElementBase)){
-				return false;
-			}else{
-				DescriptionElementBase descriptionElement = (DescriptionElementBase) droppedElement;
-				
-				if (descriptionElement.getInDescription().equals(target)) {
+		if (droppedElements != null){
+			for (Object droppedElement : droppedElements) {			
+				if (droppedElement == null){
+					MessagingUtils.warningDialog("Operation not supported yet", this, "We are currently unable to drag and drop a newly created element. Please save the editor to make this work.");
 					return false;
 				}
-				
-				descriptionElements.add(descriptionElement);
-			}			
+				if(! (droppedElement instanceof DescriptionElementBase)){
+					return false;
+				}else{
+					DescriptionElementBase descriptionElement = (DescriptionElementBase) droppedElement;
+					
+					if (descriptionElement.getInDescription().equals(target)) {
+						return false;
+					}
+					
+					descriptionElements.add(descriptionElement);
+				}			
+			}
+			
+			AbstractPostOperation operation = new MoveDescriptionElementsOperation("Move Descriptions", EditorUtil.getUndoContext(), target, descriptionElements, isCopy, null);
+			
+			EditorUtil.executeOperation(operation);
+			return true;
 		}
+		MessagingUtils.warningDialog("Operation not supported yet", this, "We are unable to drag and drop empty descriptions");
+	
+		return false;
 		
-		AbstractPostOperation operation = new MoveDescriptionElementsOperation("Move Descriptions", EditorUtil.getUndoContext(), target, descriptionElements, isCopy, null);
-		
-		EditorUtil.executeOperation(operation);
-		
-		
-		return true;
 	}
 
 	/* (non-Javadoc)
-- 
2.34.1