signal for detecting gtk app de-focus

[Steve Splonskowski <splons mac com>]

Hello,

I am attempting to find a way in my gtk app to get control (via signal  
or other means) when my application looses focus - that is when  
another application comes to the front, but my app is still running. I  
need to cleanup somethings at that point in time, but have not been  
able to determine how to get control.

thanks,
steve