Final answer:
Barbara could face charges of burglary for unlawfully entering her ex-husband's residence and theft for taking the dog, which is considered property valued at $300.
Step-by-step explanation:
Based on the described scenario, Barbara could potentially be charged with two crimes: burglary and theft. Burglary is unlawfully entering a structure with the intent to commit a crime inside, and since Barbara entered her ex-husband's house through an unlocked window, this constitutes unlawful entry. The intent here is presumed due to her subsequent action of taking the dog, which brings us to the second charge, theft. Theft is the action of taking someone else's property without permission with the intention to permanently deprive them of it. As the dog has a value and is considered property, taking it would be deemed as theft. These charges can vary by jurisdiction and specifics of the law, but generally, these are the terms under which she would be investigated and potentially charged.