Add possibility to add a widget prior to the list

[bezaou]

Hi, first of all thanks for your package.

Would it be possible to add any new widget prior to the list? returning a custom Widget in the indexedItemBuilder on index==0 wouldn't help because any additional widget would still be displayed below the header

[Dimibe]

@bezaou Why would you need to have the widget inside the list.
I recommend to just have a separate widget before the list.