If you enter a space before typing a slash, it no longer counts as a command and won't be auto-completed as such.
And it won't be executed as a slash command either!
The problem is when you are trying to use the UP-Arrow to scroll thru your last so many chats and you hit a previous slash command that you executed. The auto-complete pops up and prevents you from scrolling back to lines entered previous to that one.
but that's really beside the point of my original question.