The WPF ListBox doesn't have a DoubleClick event, at least not as far as I can tell. Is there a workaround for this issue that would let me double-click on an item to have an event handler do something with it? Thanks for your help.
You could always override the ListItem Control Template and handle the double click event inside the template, for example in an invisible border that contains the normal contents of the ListBox.
This article shows you how to use a ControlTemplate with a ListBoxItem. Beyond that, simply add the handler to the outermost element of your control template.
If you have Expression Blend, you can use it to extract the existing control template for you to modify so that you do not have to do as much work to ensure that the new list box behaves the same as the old.
It turns out there is a MouseDoubleClick event for the ListBox. I added this event to my ListBox and had the event handler process my task, copying the selected item to another ListBox. So, now whenever I double-click on an item, it gets copied.