Download manager reopens when closed if a download is active

[LummoxJR]

While downloading files, the ucjsDownloadsManager.uc.js script reopens the download manager any time the download updates, not just when a new download appears.

Steps to reproduce:

1. Begin downloading a long file. (Download manager window appears.)
2. Close download manager window. (Download manager window will spontaneously reopen.)

Expected behavior:

Closing the download manager window while a download is active should leave it closed. The window should be reopened only if the user presses Ctrl+J or a new download begins.