Add a class to a DIV tag using traits

[MarcoZucc]

I can't solve a problem related to traits in grapejs

I created a traits that acts on the DIV and SECTION tags

It should give the possibility to add a pre-determined class (contained in a drop-down) to a DIV element.
On data attributes it works for me.
If I add a class to a DIV that contains another class (example myclass) it does not work: I delete the old class.
Instead, it should add the new class to the old one.

Try adding the block "SECTION" to the editor: it has its own class "myclass" that is deleted if through the “component setting” I go to edit it

Has anyone already done something similar? I would then implement everything to use tailwind and its classes
I have made a working demo

https://jsfiddle.net/zucco/5jnt9zhL/17/

[artf]

The component updates automatically its classes if you update attributes.class (this is what your trait does), so you can simply choice another attribute name for storing your color classes and then update the real classes container on change.

[MarcoZucc]

basic behavior of the traits is as you described it: artf you are right.
But I would like to take the original classes and add a class using the traits.
Unfortunately the traits overrides all the classes that were originally associated with the block