Re: Enable / disable a Gio::SimpleAction.

[Carlo Wood <carlo alinoe com>]

On Wed, 7 Oct 2020 11:15:26 +0200
Kjell Ahlstedt <kjellahlstedt gmail com> wrote:

> Have you seen the gtkmm tutorial?
> https://developer.gnome.org/gtkmm-tutorial/3.24/gtkmm-tutorial.html
> One of the examples in the /Menus and Toolbars/ chapter has a menu
> with radio items.
>
> There is also a menu demo among the gtkmm demo programs.
> https://gitlab.gnome.org/GNOME/gtkmm/-/blob/gtkmm-3-24/demos/gtk-demo/example_menus.cc
> The demo program uses Gtk::RadioMenuItem.
>
> If you want to simplify the future upgrade of your program from
> gtkmm3 to gtkmm4, I recommend that you look at the tutorial example
> in the first place. It does not use Gtk::RadioMenuItem. There are no 
> specialized radio button classes or radio menu item classes in
> gtkmm4. (It's still possible to make GUIs with radio buttons and
> radio menu items.)

Thanks again,

I cloned https://gitlab.gnome.org/GNOME/gtkmm-documentation.git
and checked out tag "3.24.0".

I found an example that has radio items in the menu and
a toggle item. However, this information was read using
Gtk::Builder::add_from_string from a string (ui_info) with the format:

    "<interface>"
    "  <!-- menubar -->"
    "  <menu id='menu-example'>"
    "    <submenu>"
    "      <attribute name='label' translatable='yes'>_File</attribute>"
    "      <section>"
    "        <item>"

and so on.

When I put that string in an XML file "example.glade" and try
to read it, glade gives the error:

    example.glade targets Gtk+ 2.12

    But this version of Glade is for GTK+ 3 only.
    Make sure you can run this project with Glade 3.8 with no
    deprecated widgets first.

In other words, it seems that the usage of "<menu>", "<submenu>" and "<section>" etc.
is old-style, pre- GTK+ 3.

I constructed MY menu with Glade 3.36 and that produces something like:

    <?xml version="1.0" encoding="UTF-8"?>
    <!-- Generated with glade 3.36.0 -->
    <interface>
      <requires lib="gtk+" version="3.22"/>
      <object class="GtkMenu" id="PlacePiece">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <child>
          <object class="GtkMenuItem" id="PlacePieceWhitePawn">
            <property name="visible">True</property>
etc.

Most notably, when I add a radio menu item it results in
the following in the .glade file (two radio menu items shown):

    <child>
      <object class="GtkMenuItem" id="PlacepieceBlackPawn">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property
        name="action_name">PlacepieceMenu.PlacepieceBlackPawn</property>
        <property name="label" translatable="yes">Black pawn</property>
        <property name="use_underline">True</property> </object>
    </child>
    <child>
      <object class="GtkMenuItem" id="PlacepieceBlackRook">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property
        name="action_name">PlacepieceMenu.PlacepieceBlackRook</property>
        <property name="label" translatable="yes">Black rook</property>
        <property name="use_underline">True</property> </object>
    </child>

where-as the tutorial example has:

    "      <section>"
    "        <item>"
    "          <attribute name='label' translatable='yes'>Choice_A</attribute>"
    "          <attribute name='action'>win.choice</attribute>"
    "          <attribute name='target'>a</attribute>"
    "        </item>" 
    "        <item>" 
    "          <attribute name='label' translatable='yes'>Choice_B</attribute>"
    "          <attribute name='action'>win.choice</attribute>"
    "          <attribute name='target'>b</attribute>"
    "        </item>"
    "      </section>"

Since the 'action' and 'target' attributes are important in order to get
the whole to work as a radio button, I need to know how one can do this
with glade.

Or am I missing something?

Carlo