Hide blend mode popup when using refraction

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Editor/LitUI.cs

         protected MaterialProperty refractionMode = null;
         protected const string kRefractionMode = "_RefractionMode";
 
+        protected override bool showBlendModePopup
+        {
+            get { return refractionMode == null || refractionMode.floatValue == 0f; }
+        }
+
         protected void FindMaterialLayerProperties(MaterialProperty[] props)
         {
             for (int i = 0; i < m_LayerCount; ++i)
                         ++EditorGUI.indentLevel;
 
                         m_MaterialEditor.ShaderProperty(ior, Styles.refractionIORText);
+
+                        blendMode.floatValue = (float)BlendMode.Lerp;
 
                         if (mode != Lit.RefractionMode.ThinPlane)
                         {

ScriptableRenderPipeline/HDRenderPipeline/Material/Unlit/Editor/BaseUnlitUI.cs

         // See comment in LitProperties.hlsl
         const string kEmissionColor = "_EmissionColor";
 
+        bool m_ShowBlendModePopup = true;
+        protected virtual bool showBlendModePopup { get { return m_ShowBlendModePopup; } }
+
         // The following set of functions are call by the ShaderGraph
         // It will allow to display our common parameters + setup keyword correctly for them
         protected abstract void FindMaterialProperties(MaterialProperty[] props);
             SurfaceTypePopup();
             if ((SurfaceType)surfaceType.floatValue == SurfaceType.Transparent)
             {
-                BlendModePopup();
+                if (showBlendModePopup)
+                    BlendModePopup();
 
                 m_MaterialEditor.ShaderProperty(preRefractionPass, StylesBaseUnlit.transparentPrePassText);
             }