I don't honestly even know what is the right terminology to use there. Any suggestion for improvements are welcome.

Maybe Window class translation rules. since that's what is being matched?

Thanks, I like it

I'd do some changes regarding this:

• If users set this to e.g. ["--buttons 45"] they would override the --detach option (which actually should be called --no-detach or so anyways), so the service would fork off, which is not as nicely handled anymore then. So I suggest to add --detach unconditionally in the ExecStart to prevent this. I don't see any reason anybody would want to change that anyways.
• The name options is already an overloaded term from the module system, and with above change, extraOptions is more fitting, which is also the standard naming for such options.
• Unless I'm missing something, I don't see a reason --buttons 45 should be passed by default. Same with --kill which doesn't make any sense here, or does it? So I'd just make default = [] but put some examples in example = [ "--debug" "--buttons 45" ]

These defaults are based mostly on my experimentation because sadly running IMWheel without flags causes some issues

• detach is by default true so passing --detach toggles it so it doesn't detach. Which I believe makes more sense when it's ran as a service.
• kill meas that any already running IMWheel process will be killed when this one starts. I think this also make sense because otherwise result can be unpredictable
• buttons 45 is passed because without this IMWheel breaks functionality of additional mouse buttons like back and forward (tested with Logitech and MAD Rat)

Using defaults make it still possible for user to easily overwrite those things. This is why there is a pkill https://github.com/NixOS/nixpkgs/pull/71052/files#diff-ea25b843a6681ed1b7711805ec769667R64 so in case --detach is not passed (and so process is detached) IMWheel is still killed when service stops. This is also related to this comment #71052 (comment) and my reaction #71052 (comment).

so TL;DR:

• --detach is to prevent detaching which imo makes more sense for a service
• --buttons 45 is to avoid breaking addition mouse buttons with default settings (just enable = true)
• --kill is to avoid multiple IMWheel processes (whenever started manually or by systemd)
• pkill is used in cases someone overwrides defaults but doesn't pass --detach or -d

Which this in mind do you think want to change these defaults @infinisil ?

EDIT: There is also no --no-detach flag available
EDIT: Passing some aruguments twice disables it so:

imwheel -d -d has same effect as imwhell
imwheel -d -d -d has same effect as imwheel -d

This makes it a bit more problematic to make some flags mandatory.

sorry for ping @infinisil I don't want to be too pushy about this. I'm happy to implement any changes, just want to make sure you still feel we want to do them considering the comment above.

It seems regardless of any changes to the defaults, the rename from options to extraOptions should happen.

Hm okay I can see the buttons default being reasonable, but --detach and maybe --kill too can imo be added like

{
  ExecStart = "${pkgs.imwheel}/bin/imwheel" + escapeShellArgs ([
    "--detach"
    "--kill"
  ] ++ cfg.extraOptions);
}

This means even when the user doesn't specify them in extraOptions, they still get added, and the expectation is that users won't add --detach in extraOptions. It should feel like "Extra options in addition to the ones NixOS adds on its own because they always make sense to use"

Thanks @infinisil for the feedback. I've incorporate this change. just few remarks:

• I've add space behind bin/imwheel because I don't think escapeShellArgs do that. Let me know if that's not right.
• There is still the pkill on ExecStop. With these additional changes it might make sense to incorporate even change to Simple type - depends of if we want to try to protect user from shooting him/herself in foot (multiple --detach arguments case) or we want to make assumption default is good and if someone overrides it by combination of extraOptions then it's his/her thing to deal with.
• I've retested changes with nixos-rebuild -I ....