add extension to downcast web events

packages/html/src/events/pointer.rs

@@ -10,6 +10,18 @@ pub struct PointerData {
     inner: Box<dyn HasPointerData>,
 }
 
+impl PointerData {
+    /// Create a new PointerData
+    pub fn new(data: impl HasPointerData + 'static) -> Self {
+        Self::from(data)
+    }
+
+    /// Downcast this event to a concrete event type
+    pub fn downcast<T: 'static>(&self) -> Option<&T> {
+        self.inner.as_any().downcast_ref::<T>()
+    }
+}
+
 impl<E: HasPointerData> From<E> for PointerData {
     fn from(e: E) -> Self {
         Self { inner: Box::new(e) }