Subject: bug#33160: 26.1; force-mode-line-update interferes button highlight

From: Eli Zaretskii <[email-masked]>
Date: Fri, 26 Oct 2018 10:43:37 +0300

> From: Fu Yuan <[email-masked]>
> Date: Fri, 26 Oct 2018 03:29:40 -0400
> 
> Symptom: Highlight on buttons disappears when `force-mode-line-update` runs
> 
> Reproduce:
> - emacs -q
> - (run-at-time 0 0.3 'force-mode-line-update)
> - M-x customize (for it has a bunch of buttons)
> - Move cursor to a button, the highlight disappears in a blink

Could be macOS-specific?  I cannot reproduce this on MS-Windows: I see
the periodic frequent redraws (portions of the display flicker), but
the highlight doesn't disappear.