bug#50660: 28.0.50; Text artifacting when the cursor moves over text under mouse face that originally displayed a box

[Po Lu]

Eli Zaretskii <eliz@gnu.org> writes:

> Do you see any display problems with the glyph under the cursor if you
> just move the cursor inside the mouse-highlighted region?  If so, can
> you show the recipe for reproducing the problem?

Yes, starting from emacs -Q, create a buffer in fundamental-mode, and
evaluate:

  (insert (propertize "some sample text" 'face '(:box 10) 'mouse-face 
'highlight))

Highlight the text that was inserted, and move the cursor around inside
the highlighted area.  The text will begin to jump all over the place.

Thanks.