Download Manager Tweak

Allows the download manager to also open in a tab or sidebar, and adds some optional display changes.

The intent of Download Manager Tweak is in the name. It "tweaks" the Firefox download manager with small changes and doesn't completely redesign it. It makes some optional changes to its appearance and allows it to be opened in a separate window, a new tab, or the sidebar. Additional features beyond appearance include deleting a downloaded file and re-downloading a mistakenly deleted file. The various appearance changes can be disabled, if you don't like the look and just want it to open in a tab or sidebar.

DMT was broken by Firefox 26 or later. Firefox 26 uses a new download manager and the old one is no longer available. DMT needs large changes to start tweaking the new download manager. There is now a version 1.0.5 that has more features working than 1.0.2, as well as many bug fixes, including the multiple windows appearing bug.
Features still missing include: reload after a file is mistakenly deleted, and the colorful icons in the list of downloads.