GtkButtonBox::set_child_ipadding
void set_child_ipadding(int ipad_x, int ipad_y);
set_child_ipadding() sets
the amount to increase the width and height of the space requested
by the buttons.
The default settings are currently (7, 0).
Note that this method is deprecated, and that internal padding will
be set by the widget itself in future versions of GTK+.
