Fix picker won't scroll down when it hits the bottom #1544 (#1567)

helix-term/src/ui/picker.rs

@@ -500,7 +500,7 @@ impl<T: 'static> Component for Picker<T> {
         let selected = cx.editor.theme.get("ui.text.focus");
 
         let rows = inner.height;
-        let offset = self.cursor / std::cmp::max(1, (rows as usize) * (rows as usize));
+        let offset = self.cursor - (self.cursor % std::cmp::max(1, rows as usize));
 
         let files = self.matches.iter().skip(offset).map(|(index, _score)| {
             (index, self.options.get(*index).unwrap()) // get_unchecked