bug#30519: 26.0.91; Emacs hangs with flyspell overlay

[Eli Zaretskii]

> From: Nick Helm <nick@tenpoint.co.nz>
> Date: Mon, 19 Feb 2018 11:24:26 +1300
> 
> Emacs hangs when point enters a word that is highlighted by flyspell. 
> 
> I cannot reproduce this on an NS build, so I originally thought it was
> limited to the mac-port. However the maintainer reproduced it with the
> emacs-26 branch, both on GTK+ and Athena toolkits. 
> 
> Recipe:
> 
> Emacs -Q
> (setq mouse-highlight 1)
> (flyspell-mode 1)
> "Misspetl wd " ;enter some text that becomes marked by flyspell
> ;place the mouse pointer over the word "Misspetl"
> ;hold the left cursor key until point moves back to the word "Misspetl"
> 
> Emacs hangs with repeating error "Marker does not point anywhere". You
> can clear the hang by moving the mouse pointer. 

Not reproducible here.  Could this be X-specific (I tried on Windows)?