Was able to solve it by outcommenting selectionHandle in the custom keyboard style.qml file.

Thanks, worked as expected!

@maximo
Hi
It creates a new Header that draws a check box image on itself since its not possible to insert a real widget.
It then response to mouse press to make the image work as a real check box.

it checks with
if (logicalIndex == 0)

so I think it only paints this in first column.