SLife Window spontaneously reopens (Mac)

Instead of minimizing SLife (which would take up more space in the task bar) I like to close the window instead. When I do this, SLife keeps running. However, the window seems to spontaneously reopen again, with no apparent trigger on my part. It would be preferable if SLife could follow the OS X convention of running windowless, until the user clicks on the running app icon, or the app regains focus.