I am still a newbie...
My first item in the launchpad Teme icons group, is itself a group of 4 icons.
I want to "hide" it.
I succeeded to hide it in WidgetManager.js by
let parent = document.querySelector(".iconList .iconGroup");
when I increase zoom till the launchpad icons "drawer" is not seen, and then I decrease zoom again in order to see again the drawer, than the icon is automatically seen again...