internal SilverlightBridge(SynchronizationContext context)
 {
     this.context     = context;
     plugin           = new SilverlightPlugin(this);
     pluginExpression = null; // determined below
 }
 internal SilverlightBridge(SynchronizationContext context)
 {
     this.context = context;
     plugin = new SilverlightPlugin(this);
     pluginExpression = null; // determined below
 }