I see that you have an entire (albeit empty) category for this in your todo list.
Try as I may, I cannot change a List component to be multi-select. If all wx window styles could be set after widget creation, we wouldn't have a problem. The wxListBox is one of those objects that has useful window styles that cannot be imposed post-creation.
Do you think maybe the Resource Editor would be a good place to specify window styles? Maybe not. Some widgets have gobs of them. Perhaps some nice, generic interface function that enables specifying these bits at a point before component creation. Maybe some combination of both would makes sense. Hnmmm...