On 2017-05-17 11:23, Eli Zaretskii wrote:
>> For xterm.c, the relevant function seems to be x_draw_underwave.
> How about sending a patch?

I had a quick look. The current code uses a loop and draws line segments between each of the underline points.
This strategy doesn't look as pretty when using a thicker line.  Would it be OK to use XDrawLines instead?

Clément.