When deleting characters the user will positioning the cursor at the END of the character and then press backspace, but for horizontal lines created with 3 dashes (---) that rule don't count and the user will instead have to place the cursor in FRONT (or top) of the horizontal line to have it deleted. Seems easy enough in theory, but when helping people getting started with LibreOffice Writer I've observed that this feels very unnatural and is commonly causing much confusion. For example the user will first try and place the cursor at the end of the horizontal line or the bottom of it and press backspace, but when that don't work they will either start digging through the menus in a search for a solution or try highlighting the horizontal line and press Enter hoping their selection will overwrite the line (which really creates even more horizontal lines instead). A handful of examples found on the web: - https://forum.openoffice.org/en/forum/viewtopic.php?f=7&t=76971 - https://superuser.com/questions/802324/libreoffice-delete-solid-line - https://ask.libreoffice.org/en/question/64246/how-do-you-delete-a-horizontal-line/ - https://ubuntuforums.org/showthread.php?t=1948142 It would therefore be super-convenient if the user did not have to place the cursor in front or top of the line to delete it, but could backspace from the end of the horizontal line as they are expecting.
It is simply a usage issue. Because those are *not* individual characters. Rather, they are the bottom border of an otherwise empty paragraph inserted as an autocorrection action responding to the triple character(s). Its width will match the section or frame holding the empty paragraph with its autocorrected border. Deletion as with any other paragraph--select it and delete. Or with rubout/delete position at the paragraph mark (Pilcrow) for the paragraph holding the horizontal rule created by the autoformat. Toggling the formatting marks visible (<ctrl>+<F10>) makes selection of the correct paragraph more obvious. IMHO => WF =-ref-= some usage help from the ASK forum: https://ask.libreoffice.org/en/question/15711/stop-auto-line-formatting/ https://ask.libreoffice.org/en/question/36696/why-is-it-so-hard-to-add-a-horizontal-rule-in-libreoffice-4/
Considering that this is a very common question I'm not convinced that this is simply a usage issue. "Deletion as with any other paragraph--select it and delete." This is one of things users will try, but when they select the horizontal line and hit backspace/delete/enter/right-click and select cut/etc it won't remove the horizontal line. For this to actually work you would have to select multiple rows, unfortunately this is not a obvious thing you would do because you would normally only select the one thing you want to remove. Also, if the user accidentally place a horizontal line on the top of the document this wont work at all. What I've seen both in person and from many of the examples to be found on the web is that this causes a lot of frustration among users and they often just ends up making a new document instead as they are simply unable to remove it, that's why I think this actually is a usability issue which I hope Writer can do better. The only trick that work for all situations seems to be by resetting the formatting by first highlighting the horizontal line(s) and then select Format > Remove direct formatting (Ctrl+M), but this is not very discoverable so it should probably not be considered as the best option either.