If you right-click a regular button in the window list, you get a menu for
Close, Minimize, Maximize etc.

By logical extension, you would expect to be able to click on a
grouped-window button in the list, to pop up the menu listing the windows
in the group, then right-click on the the menu entry for the window in that
group that you wanted to operate on, to pop up its Close/Minimize/Maximize
menu.

Instead, you have to *right*-click on the grouped window button, which pops
up the same window list menu as before but with the 'right-click' menu for
each window added as a submenu.  This is admittedly quite clever, but I've
only just discovered it after months of playing with it :)

I won't pretend that right-clicking on a menu item is a pleasant
alternative, but we do have a precedent for it and it's probably the most
likely thing people will try and expect in this situation.  I dunno, maybe
we could compromise and support both methods...