The Diagnostic Tools window by default includes IntelliTrace events like these:
Program Output: The thread 0x16b4 has exited with code 0 (0x0).
For applications with many threads, this can be a lot of clutter. It's easy enough to filter these from the Output window. How about the Diagnostic Tools window?
You have to use Filter function that is available in the toolbar of Events tab. Click it, find Program Output item on the list and uncheck a check box next to it.