Is there any way to make the tab completion independent of capitalisation while still getting suggested all files?

zsh should come with completion definitions for a number of popular programs, among them latex. autoload -Uz compinit && compinit is basically just a way to load these completion definitions (or so the internet tells me).

Completion definitions have the ability to apply a file name pattern/mask to restrict suggested files to file types actually supported by the program.

The file name pattern in the latex completion def. (https://sourceforge.net/p/zsh/code/ci/master/tree/Completion/Unix/Command/_tex) unfortunately does not include the dtx file extension: *.(tex|TEX|texinfo|texi)(-.).

If you always want to have all files being suggested, i would perhaps suggest to not do autoload -Uz compinit && compinit. Although there is probably a reason why you want to load the completion def's , so you could instead perhaps edit (or remove) the latex completion def. file.

P.S.: I have no deeper insight into zsh, nor am i an experienced zsh user. My comment is entirely based on looking at the latex completion definition file in zsh's git repository -- so the confidence level of my comment is at best only average. I don't really know in which folder you would find that completion definition file, nor do i know what the proper way is for modifying/removing/deactivating one/some of zsh's standard completion definitions (i am concerned about possible future zsh updates possibly undoing the changes you made to the completion definition file, or similar situations...)

elgonzo‭ Thanks a lot for your investigation! This at least explains why the completion behaves in the way it does.

If you always want to have all files being suggested, i would perhaps suggest to not do autoload -Uz compinit && compinit.

The problem is that up to now, that's the only way I have found to get case independent tab completion. Without it, I can't simply tab complete cd des to cd Desktop etc. So I looks as if I have to find out where these files are stored ...

ohh, it looks like I can simply remove the problematic modules from .zcompdump

If I remove the offending entries about latex from the function

_comps=(
...
'latex' '_tex'
...
)

so that the _tex pattern, you showed in your first comment, is no longer applied to the program latex, I get all my files suggested.

elgonzo‭ Might I be able to persuade you to convert your first comment into an answer? It nicely explains what is happening!