Show download speeds in Safari

After reading this thread and with the reproducibility described here, I started to believe that this is a bug. In this thread OS X users complain that sometimes download speed is visible and sometimes not. It was suggested to completely quit Safari, open terminal and execute:

rm ~/Library/Safari/Downloads.plist

And launch Safari again. That did not work for me.

The following steps might show your download speed (80% change, your mileage may vary):

• Start a download
• Pause that download
• Close the download window
• Wait 5 seconds and open the download window
• Resuming the download
• (after closing the download window, you need to do this all over again)

Screenshot, showing visible download speed (OS X 10.8.5 and Safari 6.0.5):

I believe that the downloads popover-window has a fixed width, and if there room for the download speed it will show it, but if there isn't enough room it won't show it. In most cases though, it will show the speed if you close the window and open it again.