bug#27647: 26.0.50; Line numbers implemented natively disappear momentarily when, frame out of focus

[Eli Zaretskii]

> From: jonas <jonaswestlund101@gmail.com>
> Date: Fri, 21 Jul 2017 19:49:19 +0200
> 
> I can replicate this behavior using flycheck and flycheck-pos-tip enabled.
> Place mark at anything marked with a squiggly line, wait for the pop up, 
> 1-2 seconds later
> line numbers disappear.

Can you provide a detailed recipe, please?  I don't use flycheck, so I
don't think I understand how to reproduce the problem.

Thanks.