which event struct and union item name should be used for each event

Signed-off-by: Mattias Andrée <maandree@operamail.com>
split that information into functions

Signed-off-by: Mattias Andrée <maandree@operamail.com>
get actual event class

Signed-off-by: Mattias Andrée <maandree@operamail.com>
get event parameters

Signed-off-by: Mattias Andrée <maandree@operamail.com>
doc some functions add todo to the rest

Signed-off-by: Mattias Andrée <maandree@operamail.com>