My take on it: if there is a button (e.g., "I am back") present on a table, then MTH sees this as a table needing action and other tables then must wait in the que until the current table is dealt with. I think minimizing such a table may have the same affect as completing action, and so, prevent pile up. I'm not sure but I think that is what I found last time I piled.

PS - 14 tables! Wow.