Do any body knows how to make editable flex grid?

I am trying to put the control on every column, when user clicks on it.
I want to display the control of the same size of the selected. but some how its not working.

The combbox is not at the desired position, i am bogged down by the Twips and pixel relationship.

Can any body help me in the sameto create editable flexgrid.?

Any help will be appreciated.

Thanks