By Amalia Otet, Associate Editor Cousins Properties Inc. has entered into an agreement to purchase 777 Main St., a 980,000-square-foot Class A office tower in Fort Worth, from a joint venture operated by Crescent Real Estate Holdings L.L.C. As part of the deal, the Atlanta-based REIT will buy Greenway Plaza, a 10-building, 4.4 million-square-foot office [...]