o opaque=NO for background views

@@ -41,6 +41,7 @@
 
     self.userInteractionEnabled = YES;
     self.multipleTouchEnabled = YES;
+    self.opaque = NO;
 
     CATiledLayer *tiledLayer = [self tiledLayer];
     tiledLayer.levelsOfDetailBias = [[mapView tileSource] maxZoom] - 1;

@@ -880,6 +880,7 @@
 
     mapScrollView = [[UIScrollView alloc] initWithFrame:[self bounds]];
     mapScrollView.delegate = self;
+    mapScrollView.opaque = NO;
     mapScrollView.backgroundColor = [UIColor clearColor];
     mapScrollView.showsVerticalScrollIndicator = NO;
     mapScrollView.showsHorizontalScrollIndicator = NO;