c# - Add variables in designer for NativeActivity<T> in wf4 -

i have class extending nativeactivity

i want allow adding variables scope of activity designer. how can modify code of activity designer let me add variables?

my code

public class myactivity : nativeactivity<bool> {     public inargument<string> someinarg { get; set; }      public inargument<object> refinarg { get; set; }      public workflowdatacontext data { get; set; }      public collection<variable> variables { get; set; }      protected override void execute(nativeactivitycontext context)     {         result.set(context, true);     } } 

thanks.

surprising enough, adding getter returns empty collection - solves problem. suspect designer tries somehow access variables collection , when null returned - gives no option set variables in designer.

    public collection<variable> variables { get; } = new collection<variable>(); 

but attempt access variables results in

activity '1.1: myactivity' cannot access variable  because declared @ scope of activity '1.1: myactivity'.   activity can access own implementation variables.