Ahhh

I figured this one out

The reason winamp adds songs to the end of playlists when you rapidly double click on songs and clears a playlist when you double click on a song after waiting a few seconds is by design.

ShellExecuteEx only takes in one file at a time but the winamp guys wanted right clicking on group of songs to play all the songs in winamp. right clicking on a group of songs sends a stream of shellexecuteex. so winamp /add has two behaviors

a. if period of time since last winamp /add is really small then add to end of playlist and play
b. else - clear playlist and play song queued.

Sam