sort or not.vi Measuring column widths seems a bit overkill if you are not auto fitting.
A point of reference. A single click to sort is not usually a desired operation especially for sorts that can take some time because it's just too easy to accidentally set it off. A double click to toggle is IMO more desirable.
XML can be tricky because it's refnum-based. Use error wires to force the execution order of the invoke nodes.
The following snippet adds an attribute "attr"="1" to the <properties/> element.