Appends a stroked border rectangle inside the given outline.
The four sides of the border can have different widths and colors.
| this |
a `GtkSnapshot` |
| outline |
the outline of the border |
| border_width |
the stroke width of the border on the top, right, bottom and left side respectively. |
| border_color |
the color used on the top, right, bottom and left side. |