I'm not surprised there is a similar request already. Being able to see the entire field/variable name is useful.
As far as how to implement it, for this particular use, I like the way the code explorer does it. That is, the whole thing appears in a tooltip window in the same location thus temporarily obscuring the original text.
It would be nice if the code used to implement it in the code explorer could be reused to implement the same feature, the same way, in the Watches window.