onWindowFocus--onAttachedToWindow--onWindowVisibilityChanged--onWindowFocusChanged
1: entry: onStart---->onResume---->onAttachedToWindow----------->onWindowVisibilityChanged--visibility=0---------->onWindowFocusChanged(true)------->
2. exit: onPause---->onStop---->onWindowFocusChanged(false) ---------------------- (lockscreen)
3, exit : onPause----->onWindowFocusChanged--false-------->Launcher.Workspace, onWindowVisibilityChanged--visibility=8------------>onStop (to another activity)
4,
