Fixed a ShaderGraph issue where the right click menu doesn't work when a stack block node is selected. Fixes fogbugz 1320212. (#4288)

Author: joshua-davis

com.unity.shadergraph/CHANGELOG.md

@@ -55,6 +55,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed an issue where users can't create multiple Boolean or Enum keywords on the blackboard. [1329021](https://issuetracker.unity3d.com/issues/shadergraph-cant-create-multiple-boolean-or-enum-keywords)
 - Fixed an issue where generated property reference names could conflict with Shader Graph reserved keywords [1328762] (https://issuetracker.unity3d.com/product/unity/issues/guid/1328762/)
 - Fixed a ShaderGraph issue where ObjectField focus and Node selections would both capture deletion commands [1313943].
+- Fixed a ShaderGraph issue where the right click menu doesn't work when a stack block node is selected [1320212].
 
 - Fixed a bug when a node was both vertex and fragment exclusive but could still be used causing a shader compiler error [1316128].
 

com.unity.shadergraph/Editor/Drawing/Views/MaterialGraphView.cs

@@ -197,12 +197,20 @@ public override List<Port> GetCompatiblePorts(Port startAnchor, NodeAdapter node
 
         internal bool ResetSelectedBlockNodes()
         {
+            bool anyNodesWereReset = false;
             var selectedBlocknodes = selection.FindAll(e => e is MaterialNodeView && ((MaterialNodeView)e).node is BlockNode).Cast<MaterialNodeView>().ToArray();
             foreach (var mNode in selectedBlocknodes)
             {
                 var bNode = mNode.node as BlockNode;
                 var context = GetContext(bNode.contextData);
 
+                // Check if the node is currently floating (it's parent isn't the context view that owns it).
+                // If the node's not floating then the block doesn't need to be reset.
+                bool isFloating = mNode.parent != context;
+                if (!isFloating)
+                    continue;
+
+                anyNodesWereReset = true;
                 RemoveElement(mNode);
                 context.InsertBlock(mNode);
 
@@ -212,7 +220,7 @@ internal bool ResetSelectedBlockNodes()
             }
             if (selectedBlocknodes.Length > 0)
                 graph.ValidateCustomBlockLimit();
-            return selectedBlocknodes.Length > 0;
+            return anyNodesWereReset;
         }
 
         public override void BuildContextualMenu(ContextualMenuPopulateEvent evt)