ExitWindows kills all current processes and that creates a race with
newly started processes. Instead, simply exit and let the new process
create a new explorer.
Per-application desktop mode settings are no longer supported. Apps
can be launched in a specific desktop window by using:
explorer /desktop=name[,widthxheight] app.exe [args]
If the named desktop already exists the app is launched inside it. The
default desktop is cleverly named "default".