Change how events are handled in Effen

sky/framework/components/button_base.dart

Index: sky/framework/components/button_base.dart
diff --git a/sky/framework/components/button_base.dart b/sky/framework/components/button_base.dart
index 40c131d57134e19efcf10d741e532eccade87b27..1152c03c6f25733e3563a30b93fe1672dadda0b4 100644
--- a/sky/framework/components/button_base.dart
+++ b/sky/framework/components/button_base.dart
@@ -7,10 +7,17 @@ import '../fn.dart';
 abstract class ButtonBase extends Component {
   bool highlight = false;
 
-  ButtonBase({ Object key }) : super(key: key) {
-    events.listen('pointerdown', _handlePointerDown);
-    events.listen('pointerup', _handlePointerUp);
-    events.listen('pointercancel', _handlePointerCancel);
+  ButtonBase({ Object key }) : super(key: key);
+
+  Node buildContent();

[rafaelw, 2015/03/19 06:11:26]

I'm tempted to feel like this is the wrong pattern, that we should be using
componentization rather than inheritance for composition. This way is more
compact, though. We can continue to see how it places out.

[abarth-chromium, 2015/03/19 14:19:59]

Yeah.

+
+  Node build() {
+    return new EventTarget(
+      buildContent(),
+      onPointerDown: _handlePointerDown,
+      onPointerUp: _handlePointerUp,
+      onPointerCancel: _handlePointerCancel
+    );
   }
 
   void _handlePointerDown(_) {