Rename Widget::on_event to update

widget/src/tooltip.rs

@@ -189,7 +189,7 @@ where
             .layout(&mut tree.children[0], renderer, limits)
     }
 
-    fn on_event(
+    fn update(
         &mut self,
         tree: &mut widget::Tree,
         event: Event,
@@ -215,7 +215,7 @@ where
             shell.invalidate_layout();
         }
 
-        self.content.as_widget_mut().on_event(
+        self.content.as_widget_mut().update(
             &mut tree.children[0],
             event,
             layout,