Index: Core/Common/src/Core.Common.Controls.TreeView/DragDropHandler.cs
===================================================================
diff -u -rb060eed93e2290dbe0a36da6e5556002625b73d5 -rae6c53b67bd2ae5e49606b31fd1575eecc58620d
--- Core/Common/src/Core.Common.Controls.TreeView/DragDropHandler.cs	(.../DragDropHandler.cs)	(revision b060eed93e2290dbe0a36da6e5556002625b73d5)
+++ Core/Common/src/Core.Common.Controls.TreeView/DragDropHandler.cs	(.../DragDropHandler.cs)	(revision ae6c53b67bd2ae5e49606b31fd1575eecc58620d)
@@ -114,25 +114,16 @@
             }
 
             var treeNodeInfo = getTreeNodeInfoForData(nodeDropTarget.Tag);
+            var canDrop = treeNodeInfo.CanDrop != null && treeNodeInfo.CanDrop(nodeDragging.Tag, nodeDropTarget.Tag);
 
-            DragOperations allowedOperations = treeNodeInfo.CanDrop != null
-                                                   ? treeNodeInfo.CanDrop(nodeDragging.Tag, nodeDropTarget.Tag)
-                                                   : DragOperations.None;
+            e.Effect = canDrop ? DragDropEffects.Move : DragDropEffects.None;
 
-            e.Effect = ToDragDropEffects(allowedOperations);
-
             if (PlaceholderLocation.None == placeholderLocation)
             {
                 return;
             }
 
-            // Determine whether or not the node can be dropped based on the allowed operations.
-            // A node can also be a valid drop target if it is the root item (nodeDragging.Parent == null).
-            var dragOperations = treeNodeInfo.CanDrop != null
-                                     ? treeNodeInfo.CanDrop(nodeDragging.Tag, nodeDropTarget.Tag)
-                                     : DragOperations.None;
-
-            if (DragOperations.None != dragOperations)
+            if (canDrop)
             {
                 DrawPlaceholder(treeView, nodeOver, placeholderLocation);
             }
@@ -310,10 +301,5 @@
             }
             return loc;
         }
-
-        private DragDropEffects ToDragDropEffects(DragOperations operation)
-        {
-            return (DragDropEffects) Enum.Parse(typeof(DragDropEffects), operation.ToString());
-        }
     }
 }
\ No newline at end of file
Index: Core/Common/src/Core.Common.Controls.TreeView/TreeNodeInfo.cs
===================================================================
diff -u -rb060eed93e2290dbe0a36da6e5556002625b73d5 -rae6c53b67bd2ae5e49606b31fd1575eecc58620d
--- Core/Common/src/Core.Common.Controls.TreeView/TreeNodeInfo.cs	(.../TreeNodeInfo.cs)	(revision b060eed93e2290dbe0a36da6e5556002625b73d5)
+++ Core/Common/src/Core.Common.Controls.TreeView/TreeNodeInfo.cs	(.../TreeNodeInfo.cs)	(revision ae6c53b67bd2ae5e49606b31fd1575eecc58620d)
@@ -139,10 +139,9 @@
         /// Gets or sets a function for checking whether or not the tree node can be dropped to another location.
         /// The first <c>object</c> parameter represents the data of the tree node which is dragged.
         /// The second <c>object</c> parameter represents the data of the tree node being considered as drop target.
-        /// The <see cref="DragOperations"/> return value indicates what operation is valid when the tree node is dropped onto the drop target.
         /// </summary>
         /// <remarks>When dragging a node, the <see cref="CanDrop"/> function of the <see cref="TreeNodeInfo"/> of the drop target should be called.</remarks>
-        public Func<object, object, DragOperations> CanDrop { get; set; }
+        public Func<object, object, bool> CanDrop { get; set; }
 
         /// <summary>
         /// Gets or sets a function for checking whether or not the tree node can be inserted into the drop target at a specific index.
@@ -284,10 +283,9 @@
         /// Gets or sets a function for checking whether or not the tree node can be dropped to another location.
         /// The first <c>object</c> parameter represents the data of the tree node which is dragged.
         /// The second <c>object</c> parameter represents the data of the tree node being considered as drop target.
-        /// The <see cref="DragOperations"/> return value indicates what operation is valid when the tree node is dropped onto the drop target.
         /// </summary>
         /// <remarks>When dragging a node, the <see cref="CanDrop"/> function of the <see cref="TreeNodeInfo"/> of the drop target should be called.</remarks>
-        public Func<object, object, DragOperations> CanDrop { get; set; }
+        public Func<object, object, bool> CanDrop { get; set; }
 
         /// <summary>
         /// Gets or sets a function for checking whether or not the tree node can be inserted into the drop target at a specific index.
@@ -361,7 +359,7 @@
                               : (Func<object, object, bool>) null,
                 CanDrop = treeNodeInfo.CanDrop != null
                               ? (draggedTag, targetTag) => treeNodeInfo.CanDrop(draggedTag, targetTag)
-                              : (Func<object, object, DragOperations>) null,
+                              : (Func<object, object, bool>) null,
                 CanInsert = treeNodeInfo.CanInsert != null
                                 ? (draggedTag, targetTag) => treeNodeInfo.CanInsert(draggedTag, targetTag)
                                 : (Func<object, object, bool>) null,
Index: Core/Plugins/src/Core.Plugins.OxyPlot/Legend/LegendView.cs
===================================================================
diff -u -rb060eed93e2290dbe0a36da6e5556002625b73d5 -rae6c53b67bd2ae5e49606b31fd1575eecc58620d
--- Core/Plugins/src/Core.Plugins.OxyPlot/Legend/LegendView.cs	(.../LegendView.cs)	(revision b060eed93e2290dbe0a36da6e5556002625b73d5)
+++ Core/Plugins/src/Core.Plugins.OxyPlot/Legend/LegendView.cs	(.../LegendView.cs)	(revision ae6c53b67bd2ae5e49606b31fd1575eecc58620d)
@@ -149,14 +149,14 @@
 
         # region ChartDataCollection
 
-        private DragOperations BaseChartCanDrop(object draggedData, object targetData)
+        private bool BaseChartCanDrop(object draggedData, object targetData)
         {
             if (draggedData is ChartData)
             {
-                return DragOperations.Move;
+                return true;
             }
 
-            return DragOperations.None;
+            return false;
         }
 
         private bool BaseChartCanInsert(object draggedData, object targetData)
Index: Core/Plugins/test/Core.Plugins.OxyPlot.Test/Legend/ChartDataCollectionTreeNodeInfoTest.cs
===================================================================
diff -u -rb060eed93e2290dbe0a36da6e5556002625b73d5 -rae6c53b67bd2ae5e49606b31fd1575eecc58620d
--- Core/Plugins/test/Core.Plugins.OxyPlot.Test/Legend/ChartDataCollectionTreeNodeInfoTest.cs	(.../ChartDataCollectionTreeNodeInfoTest.cs)	(revision b060eed93e2290dbe0a36da6e5556002625b73d5)
+++ Core/Plugins/test/Core.Plugins.OxyPlot.Test/Legend/ChartDataCollectionTreeNodeInfoTest.cs	(.../ChartDataCollectionTreeNodeInfoTest.cs)	(revision ae6c53b67bd2ae5e49606b31fd1575eecc58620d)
@@ -111,24 +111,24 @@
         }
 
         [Test]
-        public void CanDrop_SourceNodeTagIsNoChartData_ReturnsDragOperationsNone()
+        public void CanDrop_SourceNodeTagIsNoChartData_ReturnsFalse()
         {
             // Setup
             var chartDataCollection = mocks.StrictMock<ChartDataCollection>(new List<ChartData>());
 
             mocks.ReplayAll();
 
             // Call
-            var validOperations = info.CanDrop(new object(), chartDataCollection);
+            var canDrop = info.CanDrop(new object(), chartDataCollection);
 
             // Assert
-            Assert.AreEqual(DragOperations.None, validOperations);
+            Assert.IsFalse(canDrop);
 
             mocks.VerifyAll();
         }
 
         [Test]
-        public void CanDrop_SourceNodeTagIsChartData_ReturnsDragOperationsMove()
+        public void CanDrop_SourceNodeTagIsChartData_ReturnsTrue()
         {
             // Setup
             var chartData = mocks.StrictMock<ChartData>();
@@ -137,16 +137,16 @@
             mocks.ReplayAll();
 
             // Call
-            var validOperations = info.CanDrop(chartData, chartDataCollection);
+            var canDrop = info.CanDrop(chartData, chartDataCollection);
 
             // Assert
-            Assert.AreEqual(DragOperations.Move, validOperations);
+            Assert.IsTrue(canDrop);
 
             mocks.VerifyAll();
         }
 
         [Test]
-        public void CanDrop_SourceNodeTagIsNoChartData_ReturnsFalse()
+        public void CanInsert_SourceNodeTagIsNoChartData_ReturnsFalse()
         {
             // Setup
             var chartDataCollection = mocks.StrictMock<ChartDataCollection>(new List<ChartData>());
@@ -163,7 +163,7 @@
         }
 
         [Test]
-        public void CanDrop_SourceNodeTagIsChartData_ReturnsTrue()
+        public void CanInsert_SourceNodeTagIsChartData_ReturnsTrue()
         {
             // Setup
             var chartData = mocks.StrictMock<ChartData>();
Index: Ringtoets/Piping/src/Ringtoets.Piping.Plugin/PipingGuiPlugin.cs
===================================================================
diff -u -rb060eed93e2290dbe0a36da6e5556002625b73d5 -rae6c53b67bd2ae5e49606b31fd1575eecc58620d
--- Ringtoets/Piping/src/Ringtoets.Piping.Plugin/PipingGuiPlugin.cs	(.../PipingGuiPlugin.cs)	(revision b060eed93e2290dbe0a36da6e5556002625b73d5)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Plugin/PipingGuiPlugin.cs	(.../PipingGuiPlugin.cs)	(revision ae6c53b67bd2ae5e49606b31fd1575eecc58620d)
@@ -702,14 +702,14 @@
             return true;
         }
 
-        private DragOperations PipingCalculationGroupContextCanDrop(object draggedData, object targetData)
+        private bool PipingCalculationGroupContextCanDrop(object draggedData, object targetData)
         {
             if (GetAsIPipingCalculationItem(draggedData) != null && NodesHaveSameParentFailureMechanism(draggedData, targetData))
             {
-                return DragOperations.Move;
+                return true;
             }
 
-            return DragOperations.None;
+            return false;
         }
 
         private static IPipingCalculationItem GetAsIPipingCalculationItem(object item)
Index: Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/TreeNodeInfos/PipingCalculationGroupContextTreeNodeInfoTest.cs
===================================================================
diff -u -rb060eed93e2290dbe0a36da6e5556002625b73d5 -rae6c53b67bd2ae5e49606b31fd1575eecc58620d
--- Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/TreeNodeInfos/PipingCalculationGroupContextTreeNodeInfoTest.cs	(.../PipingCalculationGroupContextTreeNodeInfoTest.cs)	(revision b060eed93e2290dbe0a36da6e5556002625b73d5)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/TreeNodeInfos/PipingCalculationGroupContextTreeNodeInfoTest.cs	(.../PipingCalculationGroupContextTreeNodeInfoTest.cs)	(revision ae6c53b67bd2ae5e49606b31fd1575eecc58620d)
@@ -139,10 +139,10 @@
             {
                 case DragDropTestMethod.CanDrop:
                     // Call
-                    DragOperations supportedOperations = info.CanDrop(draggedItemContext, targetGroupContext);
+                    var canDrop = info.CanDrop(draggedItemContext, targetGroupContext);
 
                     // Assert
-                    Assert.AreEqual(DragOperations.Move, supportedOperations);
+                    Assert.IsTrue(canDrop);
                     break;
                 case DragDropTestMethod.CanInsert:
                     // Call
@@ -185,10 +185,10 @@
             {
                 case DragDropTestMethod.CanDrop:
                     // Call
-                    DragOperations supportedOperations = info.CanDrop(draggedItemContext, targetGroupContext);
+                    var canDrop = info.CanDrop(draggedItemContext, targetGroupContext);
 
                     // Assert
-                    Assert.AreEqual(DragOperations.None, supportedOperations);
+                    Assert.IsFalse(canDrop);
                     break;
                 case DragDropTestMethod.CanInsert:
                     // Call