Re: gtk_combo behavior

["Emmanuel Deloget" <logout free fr>]

    Hi GTKers.

    Tony, it seems that the tutorial section 9.11 is broken (or, at 
    least, lacks an important information : the "activate" signal
    on the combo->entry is already connected to a handler in order
    to display the list popup window. This is why you may want
    to use gtk_combo_disable_activate()). But more important,
    connecting a handler to the "activate" signal does only a small
    part of the job.

> Hi all,
>
> I have a gtk_combo that I am using basically exactly as described in the
> tutorial.  It semi-works, or rather works as far as is specified, but is
> annoying to use.  Let me describe it:
>
> If the operator types in a value and hits enter, my callback gets the
> "activate" signal and responds accordingly, reading the text from the
> entry associated with the combo.  Annoyingly, the list of choices pops
> up in the window, as if the little triangle was clicked.  The operator
> has to hit ESC, or click elsewhere, to make this go away.  How can I
> prevent this?

    Do not connect to ::activate (see below) or use the 
    gtk_combo_disable_activate() function.

> Worse, when an operator clicks the little triangle, and then selects one
> of the choices, the entry text changes (which would make the operator
> suspect that the action had occurred), but my "activate" signal handler
> is not called.  If the operator then hits enter, it gets called, but
> then the list pops up again.  I suspect that I need to attach a
> "select_child" signal handler, which will act as if an "activate" for
> the entry was done, but the order in which things need to happen is not
> clear to me.  E.g., when the "select_child" signal handler is called,
> will the widget's own behavior of putting the text into the combo->entry
> widget already have occurred?

    You should better use the combo->entry::changed signal. You'll get
    it in both cases:
      a) when the usert enters text in the entry
      b) when the user selects a new child
    Moreover, you don't rely on a particular user action (ie the user
    do not have to press ENTER to validate the text - just remember
    that a lot of GUI user do not use ENTER when typing text in a 
    single line edit box)

> I looked into testgtk and (one combo inside of) glade, and they have the
> same annoying behavior for gtk_combo's.  Neither of my Gtk/Gnome books,
> nor GGAD, seem to have any advice on this.
>
> Can anyone suggest how to get the nice behavior operators will expect? 
> Or point me toward some example code that does so?  That typing into the
> entry gets behavior like an entry, but that selecting a choice is
> identical to having types that choice and hit enter?

    Connecting to the combo->entry::activate signal is not the
    way it should work, since the GtkComboBox widget allready has
    this signal handler:

/* in gtkcombo.c */

static void        
gtk_combo_activate (GtkWidget        *widget,
      GtkCombo         *combo)
{
  gtk_combo_popup_list (combo);

  if (!GTK_WIDGET_HAS_FOCUS (combo->entry))
    gtk_widget_grab_focus (combo->entry);

  gtk_grab_add (combo->popwin);
  gdk_pointer_grab (combo->popwin->window, TRUE,
      GDK_BUTTON_PRESS_MASK | 
      GDK_BUTTON_RELEASE_MASK |
      GDK_POINTER_MOTION_MASK, 
      NULL, NULL, GDK_CURRENT_TIME);
} 

    Hope it helps,

    Emmanuel

> Thanks in advance,
>
> Eric M. Monsler
>
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