@ nibl: what? no you can sort everything out in-editor with action parts. The only reason you might use Lua for dialog/talking is for lip syncing the characters talk animations to what is being said but that's easier said than done!
@ const4ntine: sure, that's what values, conditions & if queries are for. You can use them for controlling what is active, inactive, what has already been done, or has yet to be done by the player etc... see: http://wiki.visionaire-tracker.net/wiki/Conditions_and_Values