How to disable the layout's cover when resize the cell?

In version 3.6, there is a layout.setEffect(“highlight”, false) can hide the cover,
now the setEffect is disappear, how to hide the cover?

Can you provide a bit more details, why do you need to remove the cover?
It possible to make it transparent through css styles.

because i didn’t see any splitter control has a background cover except dhtmlx’s layout,
so i am unaccustomed with dhtmlx’s layout,
i don’t know why dhmltx’s splitter is not same with others’ splitters,
since i know it can be made transparent through css styles, i think it is ok.