Help pls! Wes Bunn Inventory slot don't drag&drop but widgets work.

Hi. Wes Bunn Inventory slot don’t drag&drop but widgets work.
I debug Inventory slots and i see that - signal from override function “on mouse button down” and “on drag detected” is not going.
But in the same time i attached on inventory slot event “on click” with print string and when i press button - message appear on the screen.

I think may be it’s not work cause inventory slot use objects category instead widgets? But Wes Bunn use exactly objects for “item drag” without offsets. Nothing about it don’t find in unrel docs about this theme.
I don’t understand why override functions on inventory slots not work and don’t understand why Wes Bunn don’t use offset for inventory slot and action slot? He use it for widgets and not for objects.How it’s work? Help pls.

I find answer