Hi, Sergey
Thanks. I've added the DOEVENTS to my loop and it works. And I also viewed the post your suggested, another problem come out in my mind. If I can set the runtime property "AutoYeild" to .t.; in that way,I needn't to care where I should insert a doevent clause in my loops. But I have no idear of get the object of runtime application. For _VFP is not suit for runtime application. Do you have any idear about that?