If I understand your question, you're wondering whether is hogging could be a present continuous verb in a similar sentence. The answer is yes, it could. We know that hogging is a gerund in the sample sentence because a habit can't hog the middle of a bed. Consider this sentence though:
My dog's most annoying brother is hogging the middle of the bed. By changing one word, I've changed hogging from a gerund into a present participle. (The sentence means that my dog has more than one brother, and the most annoying one is taking up too much space.)
If I understand the grammar correctly, hogging the middle of the bed is an adjective phrase in the first sentence while the middle of the bed is the direct object of the second.
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