Do you mean add some button on the grid or an additional item in the context menu? Could you please clarify?
The option will be in the context menu. Today there is already an option to expand the cell, we want one to expand all column items.
Thanks for a quick update.
Please check the following example demonstrating this functionality: https://jsfiddle.net/flexmonster/9feqzm1m/24/. For more details about adding the options to the context menu please turn to our tutorial: Customizing context menu.
Please inform me whether this solution works for you.