Currently when viewing the status of a trigger and clicking on the name, under the history section you get the option to view the graph for all the items involved in the trigger. It would be extremely useful to be able to view a combined graph with all the items (like you can do by selecting multiple items on the "latest data" page).
Of course this then prompts another issue, what if you only want to graph some of the items? As an answer, perhaps when you are taken to the combined graph, at the bottom where it shows the legend for which items are which color line, have a checkbox for each item. When you uncheck the box, it redraws the graph without that item.
This could even be reused so that when you are viewing a trigger, and click the graph for a single item, you go to the same page as with all items, just with all the other items unchecked. This would make it very easy to enable the other items or switch between them without having to go back to the previous page.