OS X has a fairly sophisticated keyboard layout handler (better than xkb IMO) that allows you to define arbitrary dead keys in addition to the usual accents. Fo

OS X has a fairly sophisticated keyboard layout handler (better than xkb IMO) that allows you to define arbitrary dead keys in addition to the usual accents. For instance, in my usual layout, I have ‘⌥G’ as a ‘dead Greek’ key, such that for example pressing ‘⌥G’ followed by ‘b’ yields ‘β’. Similarly I have dead-key layers for superscripts, subscripts, math, blackboard bold, Hebrew letters, keyboard symbols, and so on. Layers can also be chained, so, for instance, I have a fraction chain such that ‘⌥F 3 4’ yields ‘¾’. (An X-style Compose key could be done that way, though I haven't.) Ukelele¹, free software from SIL, provides a reasonably good GUI for defining and manipulating OS X keyboard layouts. ¹ http://scripts.sil.org/ukelele http://scripts.sil.org/ukelele [Edit: fixed link]