Make window draggable able to clamp to the parent window

com.unity.shadergraph/Editor/Drawing/Inspector/MasterPreviewView.cs

             {
                 WindowDockingLayout dockingLayout = new WindowDockingLayout();
                 dockingLayout.CalculateDockingCornerAndOffset(layout, parent.layout);
+                dockingLayout.ClampToParentWindow();
                 dockingLayout.ApplyPosition(this);
                 m_RecalculateLayout = false;
             }

com.unity.shadergraph/Editor/Drawing/Inspector/WindowDockingLayout.cs

             m_Size = layout.size;
         }
 
+        public void ClampToParentWindow()
+        {
+            m_HorizontalOffset = Mathf.Max(0f, m_HorizontalOffset);
+            m_VerticalOffset = Mathf.Max(0f, m_VerticalOffset);
+        }
+
         public void ApplyPosition(VisualElement target)
         {
             if (dockingLeft)

com.unity.shadergraph/Editor/Drawing/Manipulators/WindowDraggable.cs

 
         public Action OnDragFinished;
 
-        public WindowDraggable(VisualElement handle = null)
+        public WindowDraggable(VisualElement handle = null, VisualElement container = null)
+
+            if (container != null)
+                container.RegisterCallback<GeometryChangedEvent>(OnParentGeometryChanged);
         }
 
         protected override void RegisterCallbacksOnTarget()
             {
                 if (m_WindowDockingLayout.dockingLeft)
                 {
-                    target.style.positionRight = StyleValue<float>.Create(float.NaN);
+                    target.style.positionRight = StyleValue<float>.Create(float.NaN);
                 }
                 else
                 {
             {
                 if (m_WindowDockingLayout.dockingTop)
                 {
-                    target.style.positionBottom = StyleValue<float>.Create(float.NaN);
+                    target.style.positionBottom = StyleValue<float>.Create(float.NaN);
                 }
                 else
                 {
+            }
+        }
+
+        void OnParentGeometryChanged(GeometryChangedEvent geometryChangedEvent)
+        {
+            // Check if the parent window can no longer contain the target window.
+            // If the window is out of bounds, make one edge clamp to the border of the
+            // parent window.
+            if (target.layout.xMin < 0f)
+            {
+                target.style.positionLeft = StyleValue<float>.Create(0f);
+                target.style.positionRight = StyleValue<float>.Create(float.NaN);
+            }
+
+            if (target.layout.xMax > geometryChangedEvent.newRect.width)
+            {
+                target.style.positionLeft = StyleValue<float>.Create(float.NaN);
+                target.style.positionRight = StyleValue<float>.Create(0f);
+            }
+
+            if (target.layout.yMax > geometryChangedEvent.newRect.height)
+            {
+                target.style.positionTop = StyleValue<float>.Create(float.NaN);
+                target.style.positionBottom = StyleValue<float>.Create(0f);
+            }
+
+            if (target.layout.yMin < 0f)
+            {
+                target.style.positionTop = StyleValue<float>.Create(0f);
+                target.style.positionBottom = StyleValue<float>.Create(float.NaN);
             }
         }
     }

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

 
                 m_MasterPreviewView = new MasterPreviewView(assetName, previewManager, graph) { name = "masterPreview" };
 
-                WindowDraggable masterPreviewViewDraggable = new WindowDraggable();
+                WindowDraggable masterPreviewViewDraggable = new WindowDraggable(null, this);
                 m_MasterPreviewView.AddManipulator(masterPreviewViewDraggable);
                 m_GraphView.Add(m_MasterPreviewView);