Something I’ve wanted for a long time is the ability to “pop out” a cell/widget and drag it anywhere, regardless of the layout of the parent, like for a tooltip or annotation. This wouldn’t be much different than floating the cell and adding margin, except being able to drag it would be much more convenient.
Check out this thread. Draggable and floating elements are something I could not live without. I wish there was a UI for making this type of behaviour easier to configure, though!