Ah, then you really want to look for popup-killers. There are ways to prevent modal dialog boxes from appearing at all. This is used on services and servers that are sloppy or incorporate parts that were not so-designed.

You can also be more targeted, noticing that the process has a window of the expected Class to be that popup, and feeding it a message. I think some popup-killers work that way, after the fact. Others prevent them from working in the first place.

—John