Vfx/fix/context no blocks (#27)

Author: iTris666

com.unity.visualeffectgraph/CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fix for dragged parameters order when there are categories
 - Avoid NullReferenceException in Previous Position Binder" component. [Case 1242351](https://issuetracker.unity3d.com/product/unity/issues/guid/1242351/)
 - Prevent from creating a context in VisualEffectSugraphOperator by draggingfrom an output slot.
+- Don't show the blocks window when context cant have blocks
 
 ## [9.0.0] - 2020-07-09
 

com.unity.visualeffectgraph/Editor/GraphView/Elements/VFXContextUI.cs

@@ -46,6 +46,8 @@ protected override void OnNewController()
             m_CanHaveBlocks = blocks.Any(t => controller.model.AcceptChild(t.model));
         }
 
+        public bool canHaveBlocks { get => m_CanHaveBlocks; }
+
         public static string ContextEnumToClassName(string name)
         {
             if (name[0] == 'k')

com.unity.visualeffectgraph/Editor/GraphView/Views/VFXView.cs

@@ -1104,7 +1104,8 @@ void OnCreateNode(NodeCreationContext ctx)
 
             if (context != null)
             {
-                context.OnCreateBlock(point);
+                if(context.canHaveBlocks)
+                    context.OnCreateBlock(point);
             }
             else
             {