private void AddBlock_Click(object sender, RoutedEventArgs e)
        {
            BlockModel NewBlock = new BlockModel();

            NewBlock.LstBlockProp.Add(new BlockPropModel("Default"));
            ArCaBlockView blockForm = new ArCaBlockView(NewBlock, true);

            Autodesk.AutoCAD.ApplicationServices.Application.ShowModalWindow(blockForm);
        }
        private void EdtBlock_Click(object sender, RoutedEventArgs e)
        {
            //Check if there any selected block in lvBlocks
            if (lvBlocks.SelectedIndex == -1)
            {
                MessageBox.Show("Select one block first.", "Edit Block", MessageBoxButton.OK, MessageBoxImage.Exclamation);
                return;
            }
            //Edit BlockModel
            BlockModel    objBlock  = lvBlocks.SelectedValue as BlockModel;
            ArCaBlockView blockForm = new ArCaBlockView(objBlock, false);

            Autodesk.AutoCAD.ApplicationServices.Application.ShowModalWindow(blockForm);
        }