Main Menu("command") - return value?

[#1]

If I open a file via open("filename"), the command returns a reference to the data table which can be used as 

dt = open("filename");

If I trigger open via

dt = Main Menu("open")

it doesn't return a reference to the data table.

In general, is there a way, when triggering a command from the Main Menu, to get the return value?

e.g. a reference to a data table for a user defined file loader - or an error code of the AddIn?