Keep a menu open until the menu button is pressed again.

I think it's a worthwhile change if only for consistency. Maybe it could be the standard behaviour instead of having another option.

Hmm... you are right, toggle menus is more right.

A torn of menu requires manual positioning to hug the toolbar and needs repositioning when you do something like change the triggering toolbar's height. In effect I want the menu to appear as a toolbar.

I'll add the option something like "Standard position" in addition to the "Popup at cusor". TLB will place torn of menu into the same place as normal menu.