c# - Using IExtenderProvider to provide a Type property -

i trying add type property controls in winforms designer. ideally them serialised using typeof(mycompany.thetypeiused) (ala way bindingsource.datasource can serialized).

putting aside fact have not specified designer type, appears if add iextenderprovider uses 'type', property not appear in property grid. if use int or string or other type works fine.

is bug in iextenderprovider implementation or attributes etc required?

[provideproperty("commandtype", typeof (control))] public class typeextender : component, iextenderprovider {     private readonly dictionary<control, type> controlcommands;      public typeextender()     {         controlcommands = new dictionary<control, type>();     }      #region impl      bool iextenderprovider.canextend(object target)     {         var control = target control;         if (control == null)         {             return false;         }         return true;     }      [defaultvalue(null)]     public type getcommandtype(control obj)     {         if (obj == null)         {             debug.fail("non control provided type getter");             return null;         }         type commandtype;         if (controlcommands.trygetvalue(obj, out commandtype))         {             return commandtype;         }         return null;     }      public void setcommandtype(control obj, type value)     {         if (obj == null)         {             debug.fail("non control provided command setter");             return;         }         if (value == null)         {             controlcommands.remove(obj);         }         else         {             controlcommands[obj] = value;         }     }      [usedimplicitly]     private bool shouldserializecommand(object c)     {         var control = c control;         if (control == null)         {             return false;         }         type type;         if (controlcommands.trygetvalue(control, out type))         {             return type != null;         }          return false;     }      [usedimplicitly]     private void resetcommand(object c)     {         if (c control)         {             controlcommands.remove(c control);         }     }      #endregion }