My IDL's version is 7.1. I want to use the "control" to display my results in visual studio. At first, I try it in VS2008 ,there is something wrong with the "control". there is no CIDLDrawX3 class. Then I Tried it in VC++6.0 ,it worked ! It recognizes CIDLDrawX3 class. I have some confusion about how the event pro file interact with the events triggered in vc++6.0. In the example , We need to supply filename for the auto events in property sheet. And I use classwizard to write the mouse down/move/up event handler. Then all finished, I insert breakpoint in the OnMouseDownIdldrawwidget1 function, then press go ,it didn't go into the function. But it went into mousemove function. Can anyone tell me how does it work?