Ub Iwerks loved everything rounded in the backgrounds of his cartoons, even in his supposedly more realistic ComiColor fairy tales. Here are some examples from a washed out print of “The Three Bears” (1935) from one of those public domain DVDs.
The big gag in the first half of this cartoon is there are three of everything in varying sizes. Bugs Hardaway was writing for Iwerks then, wasn’t he?
How can you tell this is an Iwerks short? Radiating lines over someone’s head.
Animators were not credited on the ComiColors. Carl Stalling’s original score gets a mention.