User kokos answered the wonderful Hidden Features of C# question by mentioning the using keyword. Can you elaborate on that? What are the uses of using?
The Using scope modifier is supported in the following contexts: Remotely executed commands, started with Invoke-Command using the ComputerName, HostName, SSHConnection or Session parameters (remote session) Background jobs, started with Start-Job (out-of-process session) Thread jobs, started via Start-ThreadJob or ForEach-Object -Parallel ...
Not using by means that the technology used is incidental, and the focus is on the approach being shown to be feasible. Without more context it's impossible to say what the intended import of the sentence is and whether by would actually be better or not.
By using a joystick or a pointing device, an on-screen keyboard allows people with mobility impairments to type data. The second sentence states that the on-screen keyboard is the one that uses the joystick or pointing device to allow impaired people to type data.
Yes Yes. Either way, when the using block is exited (either by successful completion or by error) it is closed. Although I think it would be better to organize like this because it's a lot easier to see what is going to happen, even for the new maintenance programmer who will support it later:
c# - in a "using" block is a SqlConnection closed on return or ...
Updating the using keyword was specifically for templates, and (as was pointed out in the accepted answer) when you are working with non-templates using and typedef are mechanically identical, so the choice is totally up to the programmer on the grounds of readability and communication of intent.