Thanks. That is no answer :((

My winform is controled by other software. It use windows api function "sendmessage" send the windows message to my form. The function need 2 parms "form's classname & form's title". so i must change the classname to specific name like "myForm".

Sorry, maybe my question is not clear. The classname is not my class name. use the tools SPY++, you can find the form's classname is "windows.forms.app3". i want change it.

I create a winform by c# 2003. The form's classname like "windows.forms.app3",I must change the it to the particular name that like "myForm". Thanks for you help.