front end - How to have an Input cell that doubles as an Output

Motivation / examples:

• on a spreadsheet environment, each cell doubles as input and output. If we click on it, it shows the input; if we hit Enter, it shows the output;


• on this answer, I tried to mimic this kind of behaviour, but in the middle of a text cell (which is kind of an extension of the behaviour I'm asking in this post)

• the template WRI uses for many of their presentations, typically makes use of a function named LargeOverviewMouseover, where the content of the cell changes on a mouseover event, but it forces the editor to delete the input so to have a nice formatted presentation (when I use it, sometimes I end up directly editing the cell expression... ctr+shift+E, so that I don't need to retrieve the original input..., since just hiding the input generally leaves too much dead space, and is highly depending on the stylesheet...):

Question: is there a simple way of creating a Cell that doubles as Input and Output? Converting from one to the other, either on mouseover, or on clicking, or with a smarter way (so to still allow for manipulation of the output content, like dynamics, etc., without passing directly to the Input form...)?

EDIT

Ideally, a solution where the Input aspect of the cell is really an Input cell, would be best (I mean, that has all the code formatting, etc...).