Detect drag-and-drop cancellation when user pressed the Escape key

[arviedelgado]

Describe the bug

On a drag and drop operation, the user can cancel the operation by pressing the Escape key.
The value of DragEventArgs.DataTransfer.DropEffect will be none in the @ondragend event.
However, DragEventArgs.DataTransfer.DropEffect is null.

To Reproduce

<div ondragover="event.preventDefault();" style="...">
    <div draggable="true" @ondragend=OnDragEnd style="..." />
</div>

private void OnDragEnd(DragEventArgs e)
{
	if (e.DataTransfer.DropEffect == "none") // but DropEffect is null
	{
		// the user cancelled the drag operation,
		// by pressing Escape key.
	}
}

[mkArtakMSFT]

Thanks for contacting us. At the moment, Drag & Drop is not supported out of the box, so you have to write your own JSInterop logic to handle this, hence handling the Escape key.

We do plan to bring support for Drag & Drop as part of #18754