I want to implement an alphabetical list on the right side of the screen, i don't want to use a packages because they reorder my listview which i want to stay at same order, and i want to implement the onClick on a letter manualy.
So how do i implement this widget and make it stay on the side of the screen
I do NOT quite get when you say, "i don't want to use a packages because they reorder my listview which i want to stay at same order".
However, here is my implementation for your requirement. https://github.com/thanikad/alphabetical_search.
The UI is arranged using Stack, ScrollablePositionedList, and a Column. Used ScrollablePositionedList to enable the search against the ListView and then jump to the index based on the search letter selected.