backgroundFrameRate should be -1 by default for WindowedApplications

I think it's a mistake to set the background frame rate to 1 by default for desktop applications. The first Flex 4 desktop application I wrote was negatively effected by this functionality.

My application shows notifications that fade and and out whether the application is active or not. When the application wasn't activate, the fade effect was completely broken because it was happening at 1 frame per second. It's possible developers will actually release apps like this because they might not notice, or if/when they do notice, it's not easy to figure out why it's happening.