How can I determine what application is asking "Where is GrowlHelperApp.App?"

I recently upgraded to OS X 10.9 Mavericks and am now seeing a "Choose Application" dialog pop up every minute or two asking: "Where is the GrowlHelperApp.app?". I don't particularly want to buy the new version of Growl, so how can I determine which application is looking for it so that I can change it's preferences or remove it? Update: It turns out that it was an old Dashboard widget that was looking for Growl. I found this out by deleting all of my Dashboard widgets since I haven't used it in a while, but I'd still be interested in finding out how one would discover what is launching this dialog.