title: How to force Firefox to open a file which does not have a .txt extension as if it did have one?
body: <p>I have files which are just plain text, but have extension which is not <code>.txt</code>. Lets say the extension is <code>.abc</code>.</p>
  
  <p>When I click on a link that points to such a file, such as <code>file.abc</code>, I'd like Firefox to open the file as if it was <code>file.txt</code> (i.e. open it inside Firefox, listed inside Firefox itself, just like what happens when I click on <code>file.txt</code>) instead of it asking how if I want to save it or open it, and then I have to go select the application to open it with, such Notepad or whatever.</p>
  
  <p>I went to Tools → Options → Applications, but did not know what to do.</p>
  
  <p><strong>Added</strong>: Based on the comment below and the answer so far, it looks I did not explain myself well.</p>
  
  <p>I want Firefox to open the file as if the file had <code>.txt</code> extension. When you click on a link in Firefox which has <code>.txt</code>, what does Firefox do? It does not open the file in Notepad or whatever, it opens right there, inside the browser, showing the listing of the file. I want to the same to happen when <code>.abc</code> extension.</p>
  
  <p>I do not want to go around mess up with the Windows OS for this.</p>