How to add a line between headers and table?

[vulns-are-features-too]

Following /examples/table.rs, I've made a simple table. I want a horizontal line between the headers and table, but that's now shown in the example.
How can I add a horizontal line between the headers and table?

[c64zottel]

I had the same Problem: just a straight horizontal line. Took me a day, but I learned a lot about tui-rs.
Here are my two possible solutions:

• Print a string with Unicode symbol 2500:
  terminal.current_buffer_mut().set_string(1, 7, "\u{2500}────────────────────", Style::default());
• Draw a rectangle with height 1 and Borders::TOP only:

let line = Block::default().borders(Borders::TOP);
let rect = Rect { x: 0, y: 23, width: 80, height: 1 };
f.render_widget(line, rect);

There is also the possibility to use canvas, which has a struct Line:
But the default line is dotted. Maybe it's possible to change the painter or style.

I am happy with the Block-Line for now.