grid.selection.getCell() doesnt work when the row is added via API method.
Also it seems impossible to use this inside the mark callback function of the columns configuration because the only way to make
return something other than ‘undefined’ is to use
dhx.waitRedraw() which accepts a callback function.
awaitRedraw is just what you need in this case.
You need to add the callback for the row to render to operate with it, and the awaitRedraw helper does it exactly.