I have been playing the java version of Minecraft for about 3 years on a IMac. Ever since I have started playing, I have been using ctrl+click as the rb, since the Apple Mouse has only one mouse button. This method has worked in every version of Minecraft I have played. (1.8.1 - 1.12.2) But in the 1.13 snapshots and pre-releases, this has not worked. Whenever I try the ctrl+click method, it acts as if I were only pressing on the mouse. The only way that I can see around this is switching the rb control to a button on the keyboard. (a friend says he uses “F”) This, although it works, does hinder how I can play the game.