Some suggestions Rated 5 out of 5 stars

This add-on is fantastic. It looks great, and I'm really happy it has a favicon, rather than the blank one for the default download manager. However, I have one request when it comes to features, if you can find time to implement it.

When pinned as an App Tab, the download manager tab becomes constantly highlighted during a download. This works well for sites like Facebook and Gmail, but with the download manager, Firefox thinks every change in percentage is something it needs to notify me about. And so, it remains highlighted throughout the download. Is there any way to have it become highlighted only when a download has finished, failed, etc, rather than constantly being highlighted?

Oh, and opening in a background tab would be great, too, as others have requested.

Great work, though! I'm excited to see where you take this add-on.

This review is for a previous version of the add-on (0.3). 

Hmm, the app tab behavior is interesting, I hadn't tested that. I'll need to look at what Firefox looks for, there - if it's tab title changes, then I wonder if there's a way I can detect being in an app tab and then only change the title when the count of active downloads changes, which I guess makes sense for flashing.