Function def_list_item_title_fn 

pub fn def_list_item_title_fn(
    child: impl IntoUiNode,
    wgt_fn: impl IntoVar<WidgetFn<DefListItemTitleArgs>>,
) -> UiNode

P Widget function that converts DefListItemTitleArgs to widgets.

Sets the DEF_LIST_ITEM_TITLE_FN_VAR.