Hello and thanks for the example , I am getting nearer.
1) I should have worked out how to capture events by just adding an attribute to the xaml. I was thrown by ...
Handles clause requires a WithEvents variable defined in the containing type or one of its base types.
2) I can get which AutoCompleteBox generating the populating event from the sender parameter, and thus set its Item.Source dynamically.
So my autocompletebox offers the drop down and the cell displays the selected value.
However when I move to a new row the data reverts to what was originally in the row.
I have tired below to no avail.
currentRowRoomType = selectedRoomType