Scrolling with `<C-b>` does not always make virtual lines above first buffer visible

[echasnovski]

Scrolling with `` does not always make virtual lines above first buffer visible

from neovim.

[luukvbaal]

I proposed a Vim patch. Also worth noting is that Vim shows a smoothscroll marker <<< when there are hidden virtual text properties above the topline. Not sure if that is intended, or just an unintended consequence of virtual text properties affecting skipcol in Vim (as opposed to topfill for Nvim). It seems useful when there are hidden virtual lines above the first line of the buffer, do we want to show it then? I'm not sure its wanted for lines that are not the first line of the buffer.

[zeertzjq]

Fixed by #28044

[luukvbaal]

Same issue is present in Vim. I think ideally onepage() should just call scrollup()/scrolldown() so that it adjusts for filler lines and 'smoothscroll' properly.

[echasnovski]

It seems useful when there are hidden virtual lines above the first line of the buffer, do we want to show it then? I'm not sure its wanted for lines that are not the first line of the buffer.

As for me - yes. As a user, I'd want to have an indicator that there are lines above the first line and only above the first line.

[luukvbaal]

#28044 fixes this for <C-b>. Issue still exists for <C-u>, which could use the same treatment.