When does Skitch use a transparent background? I am using Skitch Plus to take screenshots of applications running on my Mac, and I have noticed it has an option to set the background.



What I still have to understand is when that option is used. As it is evident from the screenshot, it is not used when I take a screenshot of part of the screen, and (from the following screenshot) when I take a screenshot of the full screen.



Does anybody know when the transparent background is ever used?
I am using the Mac OS X Lion; is the option not working in this Mac OS X, but working for previous versions?
I haven't used Skitch, but from the context (note it is indented under a checkbox) I think the option would apply to screenshots taken of whole windows.