Function gtk_source_gutter_renderer_activate 

pub unsafe extern "C" fn gtk_source_gutter_renderer_activate(
    renderer: *mut GtkSourceGutterRenderer,
    iter: *const GtkTextIter,
    area: *const GdkRectangle,
    button: c_uint,
    state: GdkModifierType,
    n_presses: c_int,
)