Force Foreground Application Priority

Is there any sort of CLI string or a 3rd party tool that can be used to force foreground applications I'm working in to maintain their priority rather than losing their priority to apps running in the bacground that change status?

For example; if I'm entering a meeting invitation into Calendar and I receive an IM from my Jabber client as I'm entering information into the Calendar item, it takes priority over Calendar and I have to go back and either retype or start over depending on where I was. This is a huge pet peeve of mine and would like to have some way to prevent that from happening.

Thanks!