… group name.
The gradient editor submenu add 2 submenus with changing names. It was using
again bogus actions: "gradient-editor-blending-func" and
"gradient-editor-coloring-type" do nothing except for being used as name
holders.
Instead I add the concept of group name for GimpRadioAction-s and when I use a
radio action attribute as <submenu>, this submenu will use the group name (and
sync with it, if it changes).
I only translated the undo menu into GtkBuilder's .ui format for now.
The only missing part is that the icon is now shown.
Note that in various parts, I don't rely anymore on a bogus menu action (i.e.
"undo-popup" action in this case) which does nothing but has an associated label
and icon. I simply add the label and icon as submenu attribute directly in the
.ui file, which is translatable and whose strings should be parsed by gettext.
Eventually I'll just get rid of all the various "*-popup" or "*-menu" bogus
actions.
The new GimpMenu is derived from GtkMenu. Both GimpMenu and GimpMenuBar are now
implementing GimpMenuShell which allows to share a lot of the logic for filling
the menus, adding items, etc.
