Ext.ux.grid.FormRowEditing - basically allow you to edit records inside the grid (just like the row editing plugin) using custom form items (fields). In fact, FormRowEditing is a modified version of RowEditing :-)
It's on baby stage... I still have to do a bit more housekeeping (like remove the code form RowEditing not in used), and fix all the documentation.
Here is a video
I don't recommend using complex layouts due to animation issues (seen in video). :-(
Other than that... you can throw pretty much anything in there :-)
Github - https://github.com/Certun/Ext.ux.grid.FormRowEditing