Today brought not just one, but two updates! Pixelmator was bumped up to 3.7.2 with a few improvements and fixes and Pixelmator Pro moved up to 1.1.2 with a couple new (smaller) features you requested, like Command-clicking to load layers as selections.
Catch the Pixelmator 3.7.2 release notes here.
And the Pixelmator Pro 1.1.2 release notes here.