Tool panel keeps popping up

[David_Fine]

I have a clever little custom button I made (well, sort of clever) which toggles open and closed three panels which I like to access, but don't want them hanging around on the screen all the time. They are Tool, Main and Palette. When I toggle them all off, I keep finding that the Tool panel pops onto the screen all by itself and at no particular time that I can tell. Sometimes when I change a tool, like pen to selection, but not always. Any idea what makes this happen and how to stop it?