Checkbox backgrounds

[spmarsden]

The check icons ttkwidgets/assets/checked.png and unchecked.png (and I assume others) have white backgrounds. This causes a border to be visible when the background colour of a row is set. Would it be possible to make the outer background of the images transparent?

I realise that I can manually replace the images using tree.tag_configure("unchecked", image=...) and will be using this as a work around.