GTK3 message dialog created with gtk_message_dialog_new shows no icon on Fedora?

[p0ft]

I have this very simple code demonstrating a GTK3 message dialog:

test.c

#include <gtk/gtk.h>
int main (int argc, char *argv[]) {
	gtk_init (&argc, &argv);
    GtkWidget *hello = gtk_message_dialog_new (NULL, GTK_DIALOG_MODAL, GTK_MESSAGE_INFO, GTK_BUTTONS_OK, "Hello world!");
	gtk_message_dialog_format_secondary_text (GTK_MESSAGE_DIALOG (hello), "This is an example dialog.");
    gtk_dialog_run(GTK_DIALOG (hello));
    return 0;
}

When I compile the above code on my Fedora Linux 35 desktop:

gcc -o test $(pkg-config --cflags --libs gtk+-3.0) test.c  -g

And run the binary,

I don’t get an icon in the message dialog? I expect to see the system icon associated with GTK_MESSAGE_INFO in the message dialog.

If I perform the exact same steps on Ubuntu 20.04.3, I do get an icon:

[skeller (Sebastian Keller)]

The icon is added by an Ubuntu-specific patch: message-dialog-restore-traditional-look-on-unity.patch\patches\debian - ubuntu/+source/gtk+3.0 - [no description]

[ebassi (Emmanuele Bassi)]

GTK does not use icons in message dialogs.

If you want to show an icon, you’ll have to create your own GtkDialog and pack widgets inside its content area yourself.