title: Open file with association
body: <p>i made a file editor in C#, and i can open files using the 'Open' button in the toolbar, i also associated the correct file types to the program, so when i click a file with the extension *.nlp the program opens correctly, but does not open the file itself (which is quite logical since i did not implement it yet)</p>
  
  <p>now is my question, how do i implement such a thing? i want the file to be opened and loaded when i click on it.</p>
  
  <p>(btw, the file is just plain text, so nothing special, and it's for windows if that matters)</p>