Currently CAS 2.6 very quickly opens & closes a window when it is processing emails, and thus seizes focus. If you have set your email to download every few minutes, this makes it very difficult to use your computer as your keystrokes will be ignored even when using a different program (eg in word). It also makes it difficult to change CAS configurations.
Previously listed as a wish list item, sorry. Think it is a bug really!
Best wishes
Mouse