I run Minecraft on my Macbook Air with an external monitor, which is set to primary. If I move the Minecraft Launcher to the internal (secondary) monitor, login, begin playing, and pause the game/open inventory/anything that releases the mouse from the game, it will instantly and consistently crash. However, if I login on the primary monitor (thus leaving the Launcher), then move the game to the secondary monitor (either at the main menu, or after entering a world), the crash will not occur. It appears to be caused by how the cursor position is determined not taking the second screen into account properly.
I've attached one of the related crash logs. In addition, the primary (external) monitor is 1680x1050, and the internal is 1366x768. Not sure if moving from a larger to smaller monitor vs. smaller to larger makes a difference.