Question aboutusing message dialog to ask confirmation

[John M Collins]

I want to have a "do you really want to do this" type question and I'm
trying to use a message dialog thus:

GtkWidget  *dlg = gtk_message_dialog_new(GTK_WINDOW(previous),
GTK_DIALOG_DESTROY_WITH_PARENT,
 GTK_MESSAGE_QUESTION,
 GTK_BUTTONS_YES_NO, "Are you sure?");
g_signal_connect_swapped(dlg,
  "response", G_CALLBACK(gtk_widget_destroy), dlg);

Then I put

if (gtk_dialog_run(GTK_DIALOG(dlg)) == GTK_RESPONSE_YES)  {

        /* Do the thing we asked about */
}
else  {
        /* Get out of here */
}


the return value from gtk_dialog_run is never GTK_RESPONSE_YES, it's
always zero whether the Yes or No button is clicked.

However if I get rid of the "response" signal and put

retval = gtk_dialog_run(GTK_DIALOG(dlg));
gtk_widget_destroy(dlg);

if (retval ==  GTK_RESPONSE_YES)  {

        /* Do stuff */
}
else  {
        /* Get out of here */
}

It works OK.

"Is this a bug or a feature"?


John Collins Xi Software Ltd www.xisl.com

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[Eduardo M KALINOWSKI-4]

On Fri, May 16, 2008 at 3:19 PM, John M Collins <jmc@...> wrote:

> I want to have a "do you really want to do this" type question and I'm
> trying to use a message dialog thus:
>
> GtkWidget  *dlg = gtk_message_dialog_new(GTK_WINDOW(previous),
> GTK_DIALOG_DESTROY_WITH_PARENT,
>  GTK_MESSAGE_QUESTION,
>  GTK_BUTTONS_YES_NO, "Are you sure?");
> g_signal_connect_swapped(dlg,
>  "response", G_CALLBACK(gtk_widget_destroy), dlg);
>
> Then I put
>
> if (gtk_dialog_run(GTK_DIALOG(dlg)) == GTK_RESPONSE_YES)  {
>
>        /* Do the thing we asked about */
> }
> else  {
>        /* Get out of here */
> }
>
>
> the return value from gtk_dialog_run is never GTK_RESPONSE_YES, it's
> always zero whether the Yes or No button is clicked.
>
> However if I get rid of the "response" signal and put
>
> retval = gtk_dialog_run(GTK_DIALOG(dlg));
> gtk_widget_destroy(dlg);
>
> if (retval ==  GTK_RESPONSE_YES)  {
>
>        /* Do stuff */
> }
> else  {
>        /* Get out of here */
> }
>
> It works OK.
>
> "Is this a bug or a feature"?

It is a feature, and of the kind that bears to similarity to a bug.

You do not need to use gtk_signal_connect to connect to the "response"
signal if you are using the standard interface: it is already
connected. By connecting, you are probably destroying the dialog
before the value can be read, and it is surprinsing that you do not
get some random garbage.
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[Brian J. Tarricone]

On Fri, 16 May 2008 19:19:55 +0100 John M Collins wrote:

> I want to have a "do you really want to do this" type question and I'm
> trying to use a message dialog thus:
>
> GtkWidget  *dlg = gtk_message_dialog_new(GTK_WINDOW(previous),
> GTK_DIALOG_DESTROY_WITH_PARENT,
>  GTK_MESSAGE_QUESTION,
>  GTK_BUTTONS_YES_NO, "Are you sure?");
> g_signal_connect_swapped(dlg,
>   "response", G_CALLBACK(gtk_widget_destroy), dlg);
>
> Then I put
>
> if (gtk_dialog_run(GTK_DIALOG(dlg)) == GTK_RESPONSE_YES)  {
>
> /* Do the thing we asked about */
> }
> else  {
> /* Get out of here */
> }
>
>
> the return value from gtk_dialog_run is never GTK_RESPONSE_YES, it's
> always zero whether the Yes or No button is clicked.

gtk_dialog_run() also connects to the 'response' signal.  You cannot
rely on signal callbacks being called in any particular order.  In your
case, likely your handler (gtk_widget_destroy()) is getting called
before gtk_dialog_run()'s response handler, so you destroy the widget
before the gtk_dialog_run() response handler can run.

        -brian
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