Add function in master preview to update rendertexture size after next layout change

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Inspector/MasterPreviewView.cs

             m_PreviewRenderHandle.renderTexture = new RenderTexture(descriptor);
         }
 
+        public void UpdateRenderTextureOnNextLayoutChange()
+        {
+            RegisterCallback<PostLayoutEvent>(AdaptRenderTextureOnLayoutChange);
+        }
+
+        void AdaptRenderTextureOnLayoutChange(PostLayoutEvent evt)
+        {
+            UnregisterCallback<PostLayoutEvent>(AdaptRenderTextureOnLayoutChange);
+            RefreshRenderTextureSize();
+        }
+
         void OnMouseDragPreviwMesh(Vector2 deltaMouse)
         {
             Vector2 previewSize = m_PreviewTextureView.contentRect.size;

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

 
                 m_MasterPreviewView.layout = m_FloatingWindowsLayout.previewLayout.GetLayout(layout);
                 m_BlackboardProvider.blackboard.layout = m_FloatingWindowsLayout.blackboardLayout.GetLayout(layout);
+
+                m_MasterPreviewView.UpdateRenderTextureOnNextLayoutChange();
             }
             else
             {