Re:

On Mon, 2014-04-07 at 15:20 +0300, Nikita Tropin wrote:
> Howdy. I've encountered problem with gtkmm and glade. I'm using latter
> to create GUI for my app. I can't load GUI file while there are any
> GtkSourceView widget in it. gtkmm throws Gtk::BuilderError exception
> with description "Invalid object type `GtkSourceView'". What I'm doing
> wrong?

for some reason, GtkBuilder can not infer the proper type function from
the type name.

As a workaround you can instantiate all the class types you want to use
that are not part of gtk before using builder

so calling

g_warn_if_fail (gtk_source_view_get_type());

before 

Gtk::Builder::create_from_file("123.ui");

should work

BTW another problem is that you marked the ui file as a template and you
are not using it in a class definition.

greets

JP