fix: SelectedItems initial values not be rendered.

Author: jevonsflash

src/Controls/VCheckBoxGroup.xaml.cs

@@ -78,6 +78,10 @@ object newValue
             (newValue as INotifyCollectionChanged).CollectionChanged += (
                 bindable as VCheckBoxGroup
             ).VCheckBoxGroup_CollectionChanged;
+            if (oldValue == null)
+            {
+                (bindable as VCheckBoxGroup).UpdateItemSelection((IList)newValue);
+            }
         }
         else
         {

src/Controls/VCollection.xaml.cs

@@ -116,6 +116,10 @@ object newValue
             (newValue as INotifyCollectionChanged).CollectionChanged += (
                 bindable as VCollection
             ).VCollection_CollectionChanged;
+            if (oldValue == null)
+            {
+                (bindable as VCollection).UpdateItemSelection((IList)newValue);
+            }
         }
         else
         {