Open txt file with GVim from webpage link

I have a local web page with links to .txt files; I want Firefox to open the files with GVim, not in the browser window. How do I do this? In Firefox "Options" → "General" → "Applications" → "plain text document" I have selected "Use GVim (default)". However, the files continue opening in a browser tab. I did the same for PHP scripts: "Use GVim"; they open in a GVim window. Precisely the behavior I'm wanting with .txt files.