Yes Lupo, I was just saying it in case of.
So let me give you a trick I found, in order to target an element with multiple classes.
Say you have this popup that you want to target with an interaction. You can build it from scratch in order for it to have a unique "NewPopup" class. But you could reuse an existing element, who already have 2 classes: .popup.big.
Do it anyway, re-use that popup and surcharge it with your new class, you end up with .popup.big.newPopup
Now, just before starting to build your interaction, drag a dummy div, or anything, in the designer. Then give it the simgle class .newPopup.
Build your interaction, call .newPopup in the "Affect different element" dialog, it appears, select it. Build your interaction. Now before testing it, you can delete the dummy div (or any other element) you used solely to affect the class you needed to target.
Test your interaction, it indeed is targetting .popup.big.newPopup
Hope that'll work for you I have to say most of my interactions target elements with many classes and I never had a trouble.