Oh, wait, I just found a setting (thanks to finding and seeing those xml-settings) in the UI with the toggle-button.
Problem solved... That button works and remembers when closed/opened, ie. it was there all along as a special setting when the skin is in Winshade/docked mode, hidden in a drop-down (as opposed to rightclicking and selecting Options which only affects normal mode).
Case closed, Winamp-user humbled and feeling a bit silly.. and grateful for the help I got from both of you.
/Daniel