@Nonnull
	@Override
	public ItemTreeSelectionPopup<T> withMultipleSelection() {
		tree.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
		return this;
	}
@param consumer
		Consumer to run when user accepts selected items.
recaf-ui/src/main/java/software/coley/recaf/ui/control/popup/ItemTreeSelectionPopup.java