bug#38966: 27.0.60; Assertion failure in set_cursor_from_row

[martin rudalics]

> I seem to be unable to do that, so please show detailed instructions
> starting from "emacs -Q".  What I get here is a very thin single line
> of text, where I still see the cursor (partially) and can type text.

I attach a new file test-popup-3.el.  With emacs -Q load it, type F1,
then F2.  After C-x o I can move through the lower window without
seeing any cursor or text line.  I also attached two screenshots, one
before C-x o and one after.  If you look hard enough, you can spot the
remnants of the scroll bar on the lower window's mode line.

martin

test-popup-3.el
Description: Text document

capture_01072020_191510.png
Description: PNG image

capture_01072020_191636.png
Description: PNG image