Customize is a API Mod that deals with the in-game GUI. It allows the movement, rotation, flipping (stacks go in the opposite direction). Customize also makes it easier to add new "HudItems" to the game by simply defining rules for your HudItem.
This mod is currently in development but will soon be in Alpha.
I have the same problem this morning. I've re installed java and minecraft and still have the same problem.
"Sorry, but we couldn't connect to our servers. Please make sure that your are online and that Minecraft is not blocked. (ConnectException: Connection refused: connect)" I have internet connection, I can log into minecraft.net, and I've made sure minecraft is not blocked by my firewall.
I'm not sure what could be causing this except for the servers being down but, https://help.mojang.com/ says otherwise.