Add resize handle withh draggable functionality to MaterialNodeView

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Views/MaterialNodeView.cs

 using UnityEngine.MaterialGraph;
 using UnityEngine;
 using UnityEngine.Experimental.UIElements;
+using UnityEngine.Experimental.UIElements.StyleSheets;
 
 namespace UnityEditor.MaterialGraph.Drawing
 {
         List<GraphControlPresenter> m_CurrentControls;
         VisualElement m_PreviewToggle;
+        VisualElement m_ResizeHandle;
         Image m_PreviewImage;
         bool m_IsScheduled;
 
                 pickingMode = PickingMode.Ignore,
                 image = Texture2D.whiteTexture
             };
+
+
+
+            m_ResizeHandle = new VisualElement() { name = "resize", text = "" };
+            m_ResizeHandle.AddManipulator(new Draggable(OnResize));
+            Add(m_ResizeHandle);
+        }
+
+        void OnResize(Vector2 deltaSize)
+        {
+            style.width = layout.width + deltaSize.x;
+            style.height = layout.height + deltaSize.y;
         }
 
         void OnPreviewToggle()

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Resources/Styles/MaterialGraph.uss

 	background-color: rgba(0, 0, 0, 0.66);
 }
 
+MaterialNodeView > #resize {
+    background-color: rgb(0, 0, 255);
+    position-type: absolute;
+    position-right: 5;
+    position-bottom: 5;
+    width: 10;
+    height: 10;
+}
+
+MaterialNodeView > #resize:hover {
+    background-color: rgb(0, 127, 127);
+}
+
+MaterialNodeView > #resize:active {
+    background-color: rgb(0, 225, 25);
+}
+
 GridBackground {
 	grid-background-color: rgb(20, 21, 21);
 	line-color: rgb(20, 21, 21);

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Manipulators/Draggable.cs

+using System;
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+using UnityEngine.Experimental.UIElements;
+
+namespace UnityEditor.MaterialGraph.Drawing
+{
+    public class Draggable : MouseManipulator
+    {
+        Action<Vector2> m_Handler;
+
+        bool m_Active;
+
+        public Draggable(Action<Vector2> handler)
+        {
+            m_Handler = handler;
+            m_Active = false;
+            activators.Add(new ManipulatorActivationFilter()
+            {
+                button = MouseButton.LeftMouse
+            });
+        }
+
+        protected override void RegisterCallbacksOnTarget()
+        {
+            target.RegisterCallback(new EventCallback<MouseDownEvent>(OnMouseDown), Capture.NoCapture);
+            target.RegisterCallback(new EventCallback<MouseMoveEvent>(OnMouseMove), Capture.NoCapture);
+            target.RegisterCallback(new EventCallback<MouseUpEvent>(OnMouseUp), Capture.NoCapture);
+        }
+
+        protected override void UnregisterCallbacksFromTarget()
+        {
+            target.UnregisterCallback(new EventCallback<MouseDownEvent>(OnMouseDown), Capture.NoCapture);
+            target.UnregisterCallback(new EventCallback<MouseMoveEvent>(OnMouseMove), Capture.NoCapture);
+            target.UnregisterCallback(new EventCallback<MouseUpEvent>(OnMouseUp), Capture.NoCapture);
+        }
+
+        void OnMouseDown(MouseDownEvent evt)
+        {
+            target.TakeCapture();
+            m_Active = true;
+            evt.StopPropagation();
+        }
+
+        void OnMouseMove(MouseMoveEvent evt)
+        {
+            if (m_Active)
+            {
+                m_Handler(evt.localMousePosition);
+            }
+        }
+
+        void OnMouseUp(MouseUpEvent evt)
+        {
+            m_Active = false;
+            target.ReleaseCapture();
+            evt.StopPropagation();
+        }
+    }
+}

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Manipulators/Draggable.cs.meta

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