[gtkmm] Alignment of OptionMenu labels

["Dan Evison" <devison pacificit co nz>]

just a very minor question please:

Is there any way to specify that the text shown in an OptionMenu should be
centered?   It seems that by default the label in ordinary Buttons is
centered, and in OptionMenus is left-justified.

(I have a column of Buttons and OptionMenus and it would look tidier if all
were justified the same).

I've looked at the documentation but haven't spotted anything.

thanks,
Dan