In Mac OS X, when typing a dead key followed by a regular character, both the dead key and the modified character are printed. For example, if you press Option+E, followed by a, "´á " is entered in the editor. This is obviously wrong. This is probably a quirk in the Apple JVM implementation, that delivers VK events for both the dead key and the modified character, but hopefully IDEA should be able to work around it. Typing anything other than english is a pain.