似乎是为了垂直滚动条
SumList.Active := True;
SumList.VirtualRecords := True;
TDBGridEh 设计时
It is useful to use dynamic columns when the list of fields of DataSet is not known in advance.
in advance. 提前
Ehlib 学习
原文：https://www.cnblogs.com/CodeGear/p/10707175.html
