A disintegration theorem for non-second-countable etale groupoids

We give a self-contained account of a version of Renault's disintegration theorem for (twisted) C$^*$-algebras of not necessarily Hausdorff étale groupoids that can be covered by countably many open bisections.

As an application we discuss the $I$-norm and KMS-states and weights on general étale groupoid C$^*$-algebras.