Hi Thomasz
i tried your code and went happy instantly. Would love this function SOOOO much.
But with me its like this:
If all child items are unchecked i can toggle all of them between checked/uncheck with clicking parent.
But when a child is manualy checked before, it becomes NOT unchecked with clicking parent.

Is there a solution for unchecking all?
I have some checklist for rountines. And after checking all of them i wanna have them unchecked next time for later use.
Any help is appreciated.
Thanks a lot
UPDATE:
This htmls code would do what i like. But Joplin doesnot use it. Can i implement it somehow?

<input type="checkbox" />a
<input type="checkbox" />b
<input type="checkbox" />c
<input type="checkbox" />d
<input type="reset" />