Attaching an AR or AP cart .bin with incorrect size "silently" fails

I'm not sure i get the problem.... attaching an image with wrong size should fail of course. Its the missing error message?

This one is ODD

The error is correctly produced and distributed. And then vice_gtk3_message_error() is called to show the error message - but it doesn't show the error message!

This seems to be an unhandled race condition in our GTK code. This "fixes" it:

Index: src/arch/gtk3/uicart.c
===================================================================
--- src/arch/gtk3/uicart.c      (Revision 45100)
+++ src/arch/gtk3/uicart.c      (Arbeitskopie)
@@ -311,6 +311,7 @@
                 gboolean result;

                 result = attach_cart_image(get_cart_type(), get_cart_id(), filename_locale);
+                gtk_widget_destroy(dialog);
                 if (!result) {
                     vice_gtk3_message_error("VICE Error",
                             "Failed to smart-attach '%s'", filename);
@@ -322,10 +323,12 @@
                 }
                 g_free(filename);
                 g_free(filename_locale);
+            } else {
+                gtk_widget_destroy(dialog);
             }
-            gtk_widget_destroy(dialog);
             break;
     }
+                    // vice_gtk3_message_error("VICE Error", "Failed to fail");

     /* FIXME: hack to avoid the 'normal' dialog (via the menu) triggering the
      *        extra callback meant for the default cart setting page.

ie it looks like the error message is not shown, when the parent dialog is destroyed after creating the error message. I am not familiar with how this stuff should work and in particular what stuff should be blocking, or running in what context.... so no idea how to fix it properly. I am sure though that similar cases exist in the code, so this is probably not the only affected error message.

I've fixed this in trunk. Indeed the error message was destroyed along with the attach dialog, so it never showed up.

The vice_gtk3_message_error() function now accepts a parent argument so we can set the correct parent for the message box. If we cannot provide a proper parent (due to calling from a UI action or a vsync callback, or via ui_error() from the VICE thread) the parent is assumed to be the current emulator window.
I'll be updating vice_gtk3_message_info() and vice_gtk3_message_confirm() as well to allow to set proper parentage.