Could you be kind enough to post a screenshot of your widget setup and your calculations to retrieve the slot position please?
When I say widget setup I mean how are widgets organized around each others (what is inside a canvas pannel, what’s not, what’s inside some sort of box or not, such things, how you spawn them).
EDIT: Thanks already for replying so openly, I’m really interested in this as you can see 
EDIT2: Are you using the all-implemented drag & drop logic? If so how are you planning to work around the fact that you can’t trigger drag & dropping with single clicks (or at least didn’t find how to)?
EDIT3: 1337 gold ma friend 