A new feature called Open in Place lets you edit images in any document and save them right back to the same file. While most will probably edit photos before including them in a slideshow or document, the ability to edit and save to the same place will be handy for last-second alterations.
Save to Photos rolls in tighter integration to your Photos app; you can now edit and save to the same image, without creating a second file. Spotlight support is also included, so you can quickly find images you were working on with Pixelmator.
As for 8K support, that’s mobile overkill — but will be great for professionals who import pixel-dense imagery.
The update is hitting devices now. If you don’t yet have Pixelmator, it’s currently $4.99 in the App Store.