Hi Justin,
For inventory verbs- Oh man, my code for inventory gui stuff is still such a hack, just haven't got around to fixing it, something I've had on my list for forever! I've just added a quick hack to get you going- copy this over your existing PowerQuest.cs: https://www.dropbox.com/s/psiwos73ksepghc/PowerQuest.cs?dl=0. Then in PowerQuest Project Settings i've added an "Inventory Click Style". Set that to "Use Inventory". To set inventory as the active one when you want to, just use E.ActiveInventory = I.RubberChicken;
You can also add an "UnhandledEvent" fallback function to your Global Script, so it'll fall back to that if there's no 'Use' for an item. Copy this into your Global script-
IEnumerator UnhandledInteractInventory( IInventory item )
{
yield return E.Break;
}
As for verbs- Like you thought, there's not currently a way to add more verbs, another thing that's been on my to-list forever, so the way you are doing thing is currently the best way.
For the Dialog Trees question- I'm not sure what you mean exactly. The dialog tree gui should keep returning until you use the Stop() function. There is an OnStart() and OnStop() function for dialogs already, the buttons for those functions should be in the inspector when you have the Dialog Tree selected.