added CPShadow shadowViewEnclosingView

AppKit/CPShadowView.j

@@ -93,6 +93,31 @@ var LIGHT_LEFT_INSET    = 3.0,
         ]]];
 }
 
++ (id)shadowViewEnclosingView:(CPView)aView
+{
+    return [self shadowViewEnclosingView:aView withWeight:CPLightShadow];
+}
+
++ (id)shadowViewEnclosingView:(CPView)aView withWeight:(CPShadowWeight)aWeight
+{
+    var shadowView = [[CPShadowView alloc] initWithFrame:[aView frame]];
+    [shadowView setWeight:aWeight];
+    
+    var size = [shadowView frame].size,
+        width = size.width - [shadowView leftInset] - [shadowView rightInset],
+        height = size.height - [shadowView topInset] - [shadowView bottomInset],
+        enclosingView = [aView superview];
+    
+    [shadowView setHitTests:[aView hitTests]];
+    [shadowView setAutoresizingMask:[aView autoresizingMask]];
+    [aView removeFromSuperview];
+    [shadowView addSubview:aView];
+    [aView setFrame:CGRectMake([shadowView leftInset], [shadowView topInset], width, height)]
+    [enclosingView addSubview:shadowView];
+    
+    return shadowView;
+}
+
 - (id)initWithFrame:(CGRect)aFrame
 {
     self = [super initWithFrame:aFrame];