Adding files to play now list with Media Player 8

Did a search but found no answers. I'd think this would be an easy question...

With Windows Media Player 8 that came with my XP, how do I open multiple files when I'm already playing one. For example, if I'm playing an MP3 through WMP 8, if I want to click on a second MP3 and have it added to the existing main playlist (i.e., I don't want to create a playlist), how do I do that?

With the old version which showed up as mplayer2 in the program list, you could set an option to open multiple files in a new window or add to the existing window (which you could then tab through).

I know you can multi select with the CTRL key BEFORE you start playing, but once you have a file playing already, how do you add another to it?