Notice anything different about the vacant former city code-enforcement building at 3300 Main St. lately? Well, go around to the Travis St. side (at left) and you’ll see it: A sign indicating the property is for sale went up there quietly last month. So quietly, in fact, that there doesn’t appear to be any information about the sale on the website of the building’s owner, the Midtown Redevelopment Authority, which purchased the full-block property from the city in a curious deal 3 years ago for $5 million, and — as a public entity — isn’t required to pay any property taxes on it. “Everything real estate wise that Midtown does is very hush hush,” notes a reader who brought the sale to Swamplot’s attention.