Creates a desktop entry for QubesOS to launch a dvm browser.

dvmBrowser.desktop

[Desktop Entry]
Encoding=UTF-8
Name=BrowserVM
Exec=qvm-open-in-dvm %u
Terminal=false
X-MultipleArgs=false
Type=Application
Categories=Network;WebBrowser;
MimeType=x-scheme-handler/unknown;x-scheme-handler/about;text/html;text/xml;application/xhtml+xml;application/xml;application/vnd.mozilla.xul+xml;application/rss+xml;application/rdf+xml;image/gif;image/jpeg;image/png;x-scheme-handler/http;x-scheme-handler/https;

If you created a new Qube, you'll need to open a terminal and make a directory for the file first

mkdir -p ~/.local/share/applications

Then create the file.

touch ~/.local/share/applications/dvmBrowser.desktop

Then use your favorite editor to paste the above Gist into the file and save it. Then return to your terminal again.
Now you can run the command below to make it your default "browser" and when you click a link in that AppVM, a dvm will open.

xdg-settings set default-web-browser dvmBrowser.desktop