Add answer commments to some puzzling code

cura/Settings/GlobalStack.py

@@ -102,6 +102,9 @@ class GlobalStack(CuraContainerStack):
 
         # Handle the "resolve" property.
         #TODO: Why the hell does this involve threading?
+        # Answer: Because if multiple threads start resolving properties that have the same underlying properties that's
+        # related, without taking a note of which thread a resolve paths belongs to, they can bump into each other and
+        # generate unexpected behaviours.
         if self._shouldResolve(key, property_name, context):
             current_thread = threading.current_thread()
             self._resolving_settings[current_thread.name].add(key)