Each Lua function invoked from the Storyboard is passed two arguments:

script_function_name( table mapargs, string allargs)

The first argument, mapargs, is a Lua table whose keys provide the context in which the action is being invoked along with any action specific argument and parameters.  This context includes the application, screen and control the action was associated with, the currently focused control, any arguments provided to the action as well as all of the event data that cause the action to fire.

The following keys are always available inside the context’s table:

context_app

The application context of the current action

context_screen

The screen context of the current action (the current screen)

context_layer

The layer context of the current action (the current layer)

context_control

The control context of the current action (the current control)

context_row

If the context_control is a Table then this is the row index of the current cell

context_col

If the context_control is a Table then this is the column index of the current cell

context_target

The current context (app, screen, layer, or control) that the event was targeted at

context_event

The name of the event the triggered the action

context_event_data

A pointer to a Lua table containing any event data. The event data is different for each event and is defined in the event definition.

The second argument, allargs, provides a string containing the exact same string that was provided to the data arguments of the action.  

Example of using context data:

function get_context( mapargs, stringargs )
  print("triggered by event : "..mapargs.context_event)
  print("event was targeting : "..mapargs[mapargs.context_target])
  print("stringargs : ", stringargs)
end