Draws a horizontal line from (x1, y) to (x2, y) in cr using the given
style and state.
Use gtk_render_line instead
| style |
a Style |
| state_type |
a state |
| widget |
the widget |
| detail |
a style detail |
| x1 |
the starting x coordinate |
| x2 |
the ending x coordinate |
| y |
the y coordinate |
| cr |
a |