mjn:
i need to call something like the following on you:

layoutAll(bool tags)

layoutSubset(bool tags, ObjectList)

because i'm going to propagate everything that happens before any process
takes place (i.e., asking for a filename, asking whether to take tags into 
account) up to the passiveUI.  you'll only use the aggressiveUI to print 
error messages, if you have any...

di:
Make sure that in your constructor, you take in the components that's
below you, such as HUDataManager. How else are you going to call functions
on it?