Open https://en.wikipedia.org/wiki/User:Neil_P._Quinn-WMF/T106902?veaction=edit, which contains the wikitext:

{{stnlink|Gloucester}}

 One <nowiki><pre></nowiki> block

 Second <nowiki><pre></nowiki> block

Try to delete the first <pre> block. If you simply select from before the "O" in "One" to after the "k" in "block" (5-20 in the linear model) and press delete, you'll be able to delete the contents of the block, and another delete will get rid of the containing <pre> block.

However, if you select from after the "r" in the "Gloucester" template to before the "S" in "Second" (3-22 in the linear model) and press delete, the first <pre> block won't be deleted. Instead the contents of the second <pre> block will turn into plain text and jump up to the first line, beside the "Gloucester" template.