Another great tip for FireFox 3. You can have your FireFox 3 close the download manager after it finishes the downloads. It’s a small tweak in firefox 3 and it goes like this
1- Write about:config in your address bar.
2- Search for “browser.download.manager.closeWhenDone”
3- Change it’s value by double clicking it from false to true.
It’s done. Now, whenever you have a download in firefox 3, the Download Manager will automatically close when the download(s) finishes.