Hello,

Maybe there's an easier way, but the only way I could find to do this is via JavaScript. This is how I set up the ActionColumn to show the icon:

And this is my client action and JavaScript:

The JavaScript code:

var element = document.getElementById($parameters.GridWidgetId).querySelector('.datagrid-runtime');
var button = document.querySelector('.wj-state-selected .icon');
var evt = new MouseEvent("contextmenu", {
    clientX: button.getBoundingClientRect().x,
    clientY: button.getBoundingClientRect().y
});
element.dispatchEvent(evt);