[no subject]

For now I'll use C API, because C++ API does not work for me - maybe I
was using it incorrectly.

This is what I use now:

GtkBorder* inner_border = NULL;
gtk_widget_style_get(GTK_WIDGET(m_terminal.gobj()), "inner-border",
&inner_border, NULL);
// use my inner_border and then
gtk_border_free(inner_border);

I tried to use this:

Gtk::Border* inner_border = NULL;
m_terminal.get_style_property("inner-border", inner_border);

and got a warning:

Gtk-WARNING **: can't retrieve style property `inner-border' of type
`GtkBorder' as value of type `glibmm__CustomPointer_P10_GtkBorder'

Then I tried this:

Gtk::Border inner_border; // now it is not a pointer.
m_terminal.get_style_property("inner-border", inner_border);

and got a warning:

Gtk-WARNING **: can't retrieve style property `inner-border' of type
`GtkBorder' as value of type `glibmm__CustomBoxed_10_GtkBorder'

I was shooting in the dark by trying to pass a pointer or a value.
Seems to me it is a Glib::Value issue. And Gtk::Border is just a
typedef of a GtkBorder, which is a boxed type.