Grid: Button as EditorField?

So, what I'm trying to do is that I've got a field in my grid that's an image, and I'm using an image converter and HTML renderer to display those as they should be.

What I'd like, though, is that once the row is editable, I have a button that allows me to upload/update the image.  Or some way of triggering a popup window or upload.  I've seen similar examples with the ComboBox and that works well for those, but I cannot make it work with a button in the same way because it's not a Field<?>.  I think.

Is this even possible?  Or do I need to look for another solution, like a DetailsGenerator that shows up under the row?  If that's the case, then how do I make that show up while the row is being edited?  I'd like it to all be in one place, not to double click on the grid to edit everything but the picture but then trigger something different to edit the picture.

Thanks.