Load a large file -- any web server log will do fine.
With word-wrap off, scroll down 3 or 4 pages.
Turn word-wrap on
Position the caret on at least column 100 (assuming
single lines display fewer than 100 columns)
Scroll vertically so the caret is at line 6 of the
current view, but only on the second line
Turn word-wrap off
The caret is now inside the slop region, and also not visible.
It should be visible and outside the slop.