Make the drawer, popup menus, dialogs, and settings page scrollable.

sky/sdk/lib/animation/scroll_behavior.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'dart:math' as math;
 
 import 'mechanics.dart';
 import 'generators.dart';
 
 const double _kScrollFriction = 0.005;
 const double _kOverscrollFriction = 0.075;
 const double _kBounceSlopeAngle = math.PI / 512.0; // radians
 
 abstract class ScrollBehavior {
   Simulation release(Particle particle) => null;
 
   // Returns the new scroll offset.
   double applyCurve(double scrollOffset, double scrollDelta);
 }
 
 class BoundedScrollBehavior extends ScrollBehavior {
+  BoundedScrollBehavior({this.minOffset: 0.0, this.maxOffset});
+
   double minOffset;
   double maxOffset;
 
-  BoundedScrollBehavior({this.minOffset: 0.0, this.maxOffset});
-
   double applyCurve(double scrollOffset, double scrollDelta) {
     double newScrollOffset = scrollOffset + scrollDelta;
     if (minOffset != null)
       newScrollOffset = math.max(minOffset, newScrollOffset);
     if (maxOffset != null)
       newScrollOffset = math.min(maxOffset, newScrollOffset);
     return newScrollOffset;
   }
 }
 
@@ skipping 69 matching lines @@
     // reduce the portion of scrollDelta that's applied beyond 0.0. We
     // do similar things for overscroll in the other direction.
     if (newScrollOffset < 0.0) {
       newScrollOffset -= (newScrollOffset - math.min(0.0, scrollOffset)) / 2.0;
     } else if (newScrollOffset > maxScrollOffset) {
       newScrollOffset -= (newScrollOffset - math.max(maxScrollOffset, scrollOffset)) / 2.0;
     }
     return newScrollOffset;
   }
 }