misc
misc is an ABSTRACT widget, which is non-instantiable. You have to use
the derived types like gtkarrow, 

The API of misc is used on derived types like arrow.

Properties of misc widget are
    xalign:      The horizontal alignment, from 0 (left) to 1 (right). 
                 Reversed for RTL layouts.

    yalign:	 The vertical alignment, from 0 (top) to 1 (bottom)

    xpad:        The amount of space to add on the 
                 left and right of the widget, in pixels

    ypad:        The amount of space to add on the
                 top and bottom of the widget, in pixels"),

Basically align decides if its closer to bottom/top or left/right.
Padding is the space from the border, in pixels


These properties have accessors as follows:

void	gtk_misc_set_alignment (GtkMisc *misc,
				gfloat	 xalign,
				gfloat	 yalign);
void    gtk_misc_get_alignment (GtkMisc *misc,
				gfloat  *xalign,
				gfloat  *yalign);
void	gtk_misc_set_padding   (GtkMisc *misc,
				gint	 xpad,
				gint	 ypad);
void    gtk_misc_get_padding   (GtkMisc *misc,
				gint    *xpad,
				gint    *ypad);

Example
{
  gtk_misc_set_padding(&(GTK_ARROW(arrow)->misc),20,20);
}

see also: arrow