Support for background images on cards, style demo home

sky/sdk/lib/rendering/box.dart

Index: sky/sdk/lib/rendering/box.dart
diff --git a/sky/sdk/lib/rendering/box.dart b/sky/sdk/lib/rendering/box.dart
index 118e78b84223e5e39c5ce78e5d5fbd42bf7a236e..c2fed81a53b86209f9044e99eec41922ca640352 100644
--- a/sky/sdk/lib/rendering/box.dart
+++ b/sky/sdk/lib/rendering/box.dart
@@ -963,6 +963,11 @@ class RenderDecoratedBox extends RenderProxyBox {
   BoxDecoration get decoration => _painter.decoration;
   void set decoration (BoxDecoration value) {
     assert(value != null);
+    if (value.backgroundImage != null) {
+      if (_painter.decoration.backgroundImage != null)
+        _painter.decoration.backgroundImage.removeChangeListener(markNeedsPaint);

[abarth-chromium, 2015/06/26 23:35:59]

Don't we need to removeChangeListener even if value.backgroundImage == null (for
example, if _painter.decoration.backgroundImage is non-null)?

[jackson, 2015/06/29 16:53:25]

We do, thanks

+      value.backgroundImage.addChangeListener(markNeedsPaint);
+    }
     if (value == _painter.decoration)
       return;
     _painter.decoration = value;