Whether the menus will be closed if the anchor area is tapped.
For menus opened by buttons that toggle the menu, if the button is tapped
when the menu is open, the button should close the menu. But if
anchorTapClosesMenu is true, then the menu will close, and
(surprisingly) immediately re-open. This is because tapping on the button
closes the menu before the
onTap handler is called
because of it being considered to be "outside" the menu system, and then
the button (seeing that the menu is closed) immediately reopens the menu.
The result is that the user thinks that tapping on the button does
nothing. So, for button-initiated menus, this value is typically false so
that the menu anchor area is considered "inside" of the menu system and
doesn't cause it to close unless MenuController.close is called.
For menus that are positioned using MenuController.open's
parameter, it is often desirable that clicking on the anchor always closes
the menu since the anchor area isn't usually considered part of the menu
system by the user. In this case anchorTapClosesMenu should be true.
Defaults to false.
final bool anchorTapClosesMenu;