Not as far as I know. It would be a nice feature for some applications.
No its not possible, I too would love to see such a feature in the near future.
However, on that note, a new version of a dialog plugin was released recently.
Unlike most dialog box plugins, you may find this one of interest since it allows a lot more customisation over the end result, something I myself have been wanting for quite some time.
For instance, most dialog plugin's available do not allow a format such as
Instead, the layout is very restrictive, i.e one field per line.
Also something which I find interesting is how they have allowed you to create floating dialogs which remain on screen whilst you can still interact with filemaker. Most other dialog plugins do not allow this, you must interact with the dialog before control is given back to filemaker.