@gorhill I experienced a regression with 1.0.1rc3 (in contrast to 1.0.0) concerning domains with umlauts, that are not supported by uMatrix anymore (Screenshot below). I also can confirm the observation by @RadioActiveLobster, that the uMatrix window (dev version) is still too narrow, once the scroll bar pops up (which hides the last section).
@ceving R. Hill told me on Twitter to switch to the dev version (1.0.1rc3 at the moment) on AMO, that solves most of the menu width problem.