见到论坛上有过不少动态块动作控制的问题。呵呵。其实使用objectarx.net是可以操作动态块参数、动作的。嘿嘿。
先看看我的效果图，两个简单例子：【1.开关的可见性参数；2.开关的跨度距离参数（对应有拉伸动作）】 

 怎么实现，很简单。
直接修改动态块的属性值即可。 

  [CommandMethod("SetDynamicValue")]
        public void SetDynamicValue()
        {
            Editor ed = AsApp.DocumentManager.MdiActiveDocument.Editor;
            try
            {
                ObjectId blrid = ObjectId.Null;
                PromptEntityOptions peo = new PromptEntityOptions("选择动态块");
                PromptEntityResult per = ed.GetEntity(peo);
                if (per.Status == PromptStatus.OK)
                {
                    blrid = per.ObjectId;
                }
                else return;
                Database db = HostApplicationServices.WorkingDatabase;
                using (Transaction tra = db.TransactionManager.StartTransaction())
                {
                    Entity ent = (Entity)tra.GetObject(blrid, OpenMode.ForWrite);
                    if (ent is BlockReference)
                    {
                        BlockReference blr = ent as BlockReference;
                        if (blr.IsDynamicBlock)
                        {
                            foreach (DynamicBlockReferenceProperty dbrp in blr.DynamicBlockReferencePropertyCollection)
                            {
                                if (dbrp.PropertyName == "可见性")
                                {
                                    if (dbrp.Value.ToString() == "断开")
                                        dbrp.Value = "闭合";
                                    else
                                        dbrp.Value = "断开";
                                }
                                if (dbrp.PropertyName == "距离")
                                {
                                    dbrp.Value = Convert.ToDouble(dbrp.Value.ToString()) + 5;
                                }
                            }
                        }
                    }
                    tra.Commit();
                }
            }
            catch (System.Exception exc)
            {
                ed.WriteMessage("Error:" + exc.Message + exc.StackTrace);
            }
        }