See #2898. Fix bug where UI data was not refreshed when you switched active materials.

src/blenderbim/blenderbim/bim/handler.py

@@ -101,6 +101,10 @@ def active_object_callback():
     refresh_ui_data()
 
 
+def active_material_index_callback(obj, data):
+    refresh_ui_data()
+
+
 def subscribe_to(object, data_path, callback):
     try:
         subscribe_to = object.path_resolve(data_path, False)

src/blenderbim/blenderbim/bim/ifc.py

@@ -320,6 +320,7 @@ class IfcStore:
             blenderbim.bim.handler.subscribe_to(obj, "diffuse_color", blenderbim.bim.handler.color_callback)
         elif isinstance(obj, bpy.types.Object):
             blenderbim.bim.handler.subscribe_to(obj, "mode", blenderbim.bim.handler.mode_callback)
+            blenderbim.bim.handler.subscribe_to(obj, "active_material_index", blenderbim.bim.handler.active_material_index_callback)
 
         for listener in IfcStore.element_listeners:
             listener(element, obj)