Cloning a .desktop file: Alt+Tab doesn't distinguish new app from original

[Kerrick Staley <mail kerrickstaley com>]

Hello,

I've created a custom .desktop file for Chromium which launches it with development-related flags (the original chromium.desktop is still in place). This "Dev Chromium" launcher works, except that the Alt+Tab switcher thinks that Dev Chromium windows are Chromium windows; when Dev Chromium is launched, Alt+Tab shows an entry for "Chromium" with the original Chromium icon. If the Dev Chromium is launched alongside the regular Chromium, all windows from both apps are grouped together. How can I get Alt+Tab to treat the two apps as distinct?

Here are the contents of dev_chromium.desktop:

[Desktop Entry]

Version=1.0

Name=Dev Chromium

Comment=Develop websites

Exec=chromium --user-data-dir=.config/dev_chromium --allow-file-access-from-files --js-flags='--harmony-proxies' %U

Terminal=false

Icon=dev_chromium

Type=Application

Categories=GTK;Network;WebBrowser;

MimeType=text/html;text/xml;application/xhtml+xml;text/mml;x-scheme-handler/http;x-scheme-handler/https;

Thanks,

Kerrick