Add overlay support in iced_pure and port PickList 🎉

pure/src/widget/column.rs

@@ -1,4 +1,5 @@
 use crate::flex;
+use crate::overlay;
 use crate::widget::{Element, Tree, Widget};
 
 use iced_native::event::{self, Event};
@@ -216,6 +217,15 @@ where
             child.as_widget().hash_layout(state);
         }
     }
+
+    fn overlay<'b>(
+        &'b mut self,
+        tree: &'b mut Tree,
+        layout: Layout<'_>,
+        renderer: &Renderer,
+    ) -> Option<overlay::Element<'b, Message, Renderer>> {
+        overlay::from_children(&mut self.children, tree, layout, renderer)
+    }
 }
 
 impl<'a, Message, Renderer> Into<Element<'a, Message, Renderer>>