[求助：]请问vb.net怎样全选模型空间的图形 然后判断是否为块

'获取当前活动文档的Editor对象
        Dim ed As Editor = Application.DocumentManager.MdiActiveDocument.Editor
        Dim db As Database = HostApplicationServices.WorkingDatabase
 '定义过滤条件
        Dim values() As TypedValue = {New TypedValue(DxfCode.Start, "INSERT")}
        '建立过滤器
        Dim sfilter As New SelectionFilter(values)
        '返回选择集的用户提示类.
        Dim resSel As PromptSelectionResult
        resSel = ed.SelectAll(sfilter)
 If resSel.Status  PromptStatus.OK Then 
             ' 得到选择集中所有对象的ObjectId集合.
        Dim ids As ObjectId() = resSel.Value.GetObjectIds()
        End If