I found this info on the Firefox Builds board on mozillaZine. Some of you may recall from Firefox 1.5.0.* builds the download manager would keep a history of your downloads. By default it would retain this history until you choose to clear the list or if you changed the settings via a menu option.
Due to possible performance issues associated with having long download list, Firefox 2 by default clears the list as soon as the download is completed. You can change this option by going to Tools -> Options -> Privacy and checking Remember what I’ve downloaded. However there is a third option to retain the list until the browser exits, but this can only be set via an about:config entry:
- Click the about:config button (if you have the extension) or open a new tab and type about:config in the address bar
- In the filter field enter browser.download.manager.retention
- double-click on the entry and enter the corresponding number below:
- 0 ~ List clears when download is completed
- 1 ~ List clears when you exit the browser
- 2 ~ List clears only via ‘Clean Up’ button
- Click OK
- Close about:config editor or tab
Keep in mind the “performance issues” were NOT fixed so the change in the default behavior for the download manger was only a band aid.