event.register(event.mousedown, function(...) print(...) end)
event.unregister(event.mousedown, somefunc)
mouseclick event split into mousedown, mouseup, mousemove, mousewheel
keypress event split into keypress, keyrelease, textinput. key* events only contain keycode and scancode, don't attempt to represent a letter (was very broken at this before). Also have helpful shift/ctrl/alt flags passed in. textinput just represents inserted text, can probably even handle foreign characters.
register_step replaced with event.tick event
All legacy register_* and unregister_ functions are removed. There is a compatibility lua script, might embed it later. tpt.set_shortcuts / tpt.test also removed. event.getmodifiers added, just a misc function to get the currently held modifiers
Lots of code duplication to handle each event is removed, it's not handled in a more generic way. Although the Event class / child classes could use some work.